Exhibit 99.1

FOR IMMEDIATE RELEASE

PROSPERITY BANCSHARES, INC.^®

REPORTS SECOND QUARTER

2017 EARNINGS

HOUSTON, July 26, 2017. Prosperity Bancshares, Inc.^® (NYSE: PB), the parent company of Prosperity Bank^® (collectively, “Prosperity”), reported net income for the quarter ended June 30, 2017 of $68.554 million or $0.99 per diluted common share. Additionally, nonperforming assets remain low at 0.24% of second quarter average interest-earning assets.

“Prosperity reported $68.554 million in net income for the second quarter of 2017.  These results reflect a 15.39% annualized return on tangible common equity and a 1.22% annualized return on quarterly average assets.  These returns are some of the best in the business and are evidence of Prosperity’s strong core deposit base, efficient operations and sound asset quality,” said David Zalman, Prosperity’s Chairman and Chief Executive Officer.

“Further, Prosperity has seen solid loan growth over the last three quarters, with loans increasing 5.1% on an annualized basis during the second quarter of 2017 and 4.9% on an annualized basis during the first quarter of 2017,” continued Zalman.

“Texas and Oklahoma have continued to rebound from the downturn in the oil business. Texas employers added more than 40,000 jobs in June 2017, which brings Texas to an annualized job growth rate of 2.7%, up from 2.4% in May and in line with job growth nationally.  The Texas unemployment rate fell to 4.6% in June from 4.8% in May.  The recent acceleration in job growth led the Federal Reserve Bank of Dallas to boost its forecast for employment growth in Texas to 2.8%,” added Zalman.

“With a better economy, loan growth and a strong pipeline of approved but unfunded loans, we look forward to a solid second half of 2017,” concluded Zalman.

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Results of Operations for the Three Months Ended June 30, 2017

Net income was $68.554 million⁽²⁾ for the three months ended June 30, 2017 compared with $68.071 million⁽³⁾ for the same period in 2016. Net income per diluted common share was $0.99 for the three months ended June 30, 2017 compared with $0.98 for the same period in 2016. Annualized returns on average assets, average common equity and average tangible common equity for the three months ended June 30, 2017 were 1.22%, 7.36% and 15.39%⁽¹⁾, respectively.  Prosperity’s efficiency ratio (excluding credit loss provisions, net gains and losses on the sale of assets and securities and taxes) was 42.34%⁽¹⁾ for the three months ended June 30, 2017.

Net interest income before provision for credit losses for the three months ended June 30, 2017 was $152.231 million compared with $158.467 million during the same period in 2016, a decrease of $6.236 million or 3.9%. This change was primarily due to a $4.833 million decrease in loan discount accretion. Linked quarter net interest income before provision for credit losses decreased $204 thousand or 0.1% to $152.231 million compared with $152.435 million during the three months ended March 31, 2017.

The net interest margin on a tax equivalent basis was 3.14% for the three months ended June 30, 2017, compared with 3.37% for the same period in 2016. This change was primarily due to a $4.833 million decrease in loan discount accretion. On a linked quarter basis the net interest margin was 3.14% compared with 3.20% for the three months ended March 31, 2017.

Noninterest income was $27.780 million for the three months ended June 30, 2017 compared with $28.473 million for the same period in 2016, a decrease of $693 thousand or 2.4%. This change was primarily due to the net loss on sale of assets, partially offset by the gain on sale of securities. The sale of assets was primarily related to the sale of an aircraft acquired in a previous acquisition that was leased to a third party. On a linked quarter basis, noninterest income decreased $3.044 million or 9.9% compared with the three months ended March 31, 2017. This change was primarily due to the net loss on sale of assets, partially offset by the gain on sale of securities.

Noninterest expense was $76.442 million for the three months ended June 30, 2017 compared with $79.235 million for the same period in 2016, a decrease of $2.793 million or 3.5%. This change was primarily due to a decrease in salaries and benefits and core deposit intangibles amortization. On a linked quarter basis, noninterest expense decreased $1.620 million or 2.1% compared with the three months ended March 31, 2017. This change was primarily due to a decrease in salaries and benefits.

Results of Operations for the Six Months Ended June 30, 2017

Net income was $137.119 million⁽⁴⁾ for the six months ended June 30, 2017 compared with $137.022 million⁽⁵⁾ for the same period in 2016.  Net income per diluted common share was $1.97 for the six months ended June 30, 2017 compared with $1.96 for the same period in 2016. Annualized returns on average assets, average common equity and average tangible common equity for the six months ended June 30, 2017 were 1.22%, 7.41% and 15.60%⁽¹⁾, respectively.  Prosperity’s efficiency ratio (excluding credit loss provisions, net gains and losses on the sale of assets and securities and taxes) was 42.68%⁽¹⁾ for the six months ended June 30, 2017.

Net interest income before provision for credit losses for the six months ended June 30, 2017 was $304.666 million compared with $324.724 million for the same period in 2016, a decrease of $20.058 million or 6.2%. This change was primarily due to a $14.574 million decrease in loan discount accretion.

The net interest margin on a tax equivalent basis for the six months ended June 30, 2017 was 3.17% compared with 3.43% for the same period in 2016. This change was primarily due to a $14.574 million decrease in loan discount accretion.

Noninterest income was $58.604 million for the six months ended June 30, 2017 compared with $59.266 million for the same period in 2016, a decrease of $662 thousand or 1.1%. This change was primarily due to the net loss on sale of assets and a decrease in brokerage income, partially offset by the gain on sale of securities and an increase in service charges on deposit accounts. The sale of assets was primarily related to the sale of an aircraft acquired in a previous acquisition that was leased to a third party.

Noninterest expense was $154.504 million for the six months ended June 30, 2017 compared with $159.763 million for the same period in 2016, a decrease of $5.259 million or 3.3%.  This change was primarily due to a decrease in salaries and benefits and core deposit intangibles amortization.

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Balance Sheet Information

At June 30, 2017, Prosperity had $22.297 billion in total assets, an increase of $500.233 million or 2.3%, compared with $21.796 billion at June 30, 2016.

Loans at June 30, 2017 were $9.864 billion, an increase of $214.011 million or 2.2%, compared with $9.650 billion at June 30, 2016. Linked quarter loans increased $124.766 million or 1.3% (5.1% annualized) from $9.739 billion at March 31, 2017.

As part of its commercial and industrial lending activities, Prosperity extends credit to oil and gas production and service companies. Oil and gas production loans are loans to companies directly involved in the exploration and/or production of oil and gas. Oil and gas service loans are loans to companies that provide services for oil and gas production and exploration. At June 30, 2017, oil and gas loans totaled $287.815 million or 2.9% of total loans, of which $115.358 million were to production companies and $172.457 million were to service companies. This compares with total oil and gas loans of $328.409 million or 3.4% of total loans at June 30, 2016, of which $156.734 million were to production companies and $171.675 million were to service companies. At March 31, 2017, oil and gas loans totaled $267.445 million or 2.8% of total loans, of which $108.267 million were production loans and $159.178 million were service loans.

Deposits at June 30, 2017 were $17.071 billion, a decrease of $148.615 million or 0.9%, compared with $17.219 billion at June 30, 2016. Linked quarter deposits increased $34.958 million or 0.2% from $17.036 billion at March 31, 2017.

Asset Quality

Nonperforming assets totaled $47.618 million or 0.24% of quarterly average interest-earning assets at June 30, 2017, compared with $52.130 million or 0.27% of quarterly average interest-earning assets at June 30, 2016, and $41.199 million or 0.21% of quarterly average interest-earning assets at March 31, 2017. The linked quarter change was primarily due to one commercial and industrial loan placed on nonaccrual during the second quarter 2017.

The allowance for credit losses was $83.783 million or 0.85% of total loans at June 30, 2017, $83.826 million or 0.87% of total loans at June 30, 2016 and $84.095 million or 0.86% of total loans at March 31, 2017.  Excluding loans acquired that are accounted for under FASB Accounting Standards Codification (“ASC”) Topics 310-20 and 310-30, the allowance for credit losses was 0.93%⁽¹⁾ of remaining loans as of June 30, 2017, compared with 1.01%⁽¹⁾ at June 30, 2016 and 0.96%⁽¹⁾ at March 31, 2017.

The provision for credit losses was $2.750 million for the three months ended June 30, 2017 compared with $6.000 million for the three months ended June 30, 2016 and $2.675 million for the three months ended March 31, 2017.  The provision for credit losses was $5.425 million for the six months ended June 30, 2017 compared with $20.000 million for the six months ended June 30, 2016.

Net charge-offs were $3.062 million for the three months ended June 30, 2017 compared with $5.888 million for the three months ended June 30, 2016 and $3.906 million for the three months ended March 31, 2017. Net charge-offs for the second quarter of 2017 were primarily comprised of one commercial and industrial loan. Net charge-offs were $6.968 million for the six months ended June 30, 2017 compared with $17.558 million for the six months ended June 30, 2016.

Conference Call

Prosperity’s management team will host a conference call on Wednesday, July 26, 2017 at 10:30 a.m. Eastern Time (9:30 a.m. Central Time) to discuss Prosperity’s second quarter 2017 earnings. Individuals and investment professionals may participate in the call by dialing 877-883-0383. The elite entry number is 7554104.

Alternatively, individuals may listen to the live webcast of the presentation by visiting Prosperity’s website at www.prosperitybankusa.com.  The webcast may be accessed from Prosperity’s home page by selecting “Presentations & Calls” from the drop-down menu on the Investor Relations tab and following the instructions.

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Non-GAAP Financial Measures

Prosperity’s management uses certain non−GAAP financial measures to evaluate its performance. Specifically, Prosperity reviews tangible book value per share, return on average tangible common equity, tangible equity to tangible assets ratio and the efficiency ratio, excluding net gains and losses on the sale of assets and securities.  Further, as a result of acquisitions and the related purchase accounting adjustments, Prosperity uses certain non-GAAP measures and ratios that exclude the impact of these items to evaluate its allowance for credit losses to total loans (excluding acquired loans accounted for under ASC Topics 310-20, “Receivables-Nonrefundable Fees and Other Costs” and 310-30, “Receivables-Loans and Debt Securities Acquired with Deteriorated Credit Quality”).  Prosperity believes these non-GAAP financial measures provide information useful to investors in understanding Prosperity’s financial results and that their presentation, together with the accompanying reconciliations, provides a more complete understanding of factors and trends affecting Prosperity’s business and allows investors to view performance in a manner similar to management, the entire financial services sector, bank stock analysts and bank regulators. Further, Prosperity believes that these non-GAAP financial measures provide useful information by excluding certain items that may not be indicative of its core operating earnings and business outlook.  These non-GAAP financial measures should not be considered a substitute for, nor of greater importance than, GAAP basis measures and results; Prosperity strongly encourages investors to review its consolidated financial statements in their entirety and not to rely on any single financial measure. Because non-GAAP financial measures are not standardized, it may not be possible to compare these financial measures with other companies’ non-GAAP financial measures having the same or similar names. Please refer to the “Notes to Selected Financial Data” at the end of this Earnings Release for a reconciliation of these non-GAAP financial measures to the nearest respective GAAP financial measures.

Dividend

Prosperity Bancshares, Inc. declared a third quarter cash dividend of $0.34 per share, to be paid on October 2, 2017 to all shareholders of record as of September 15, 2017.

Prosperity Bancshares, Inc. ®

As of June 30, 2017, Prosperity Bancshares, Inc. ^® is a $22.297 billion Houston, Texas based regional financial holding company, formed in 1983. Operating under a community banking philosophy and seeking to develop broad customer relationships based on service and convenience, Prosperity offers a variety of traditional loan and deposit products to its customers, which consist primarily of small and medium sized businesses and consumers. In addition to established banking products, Prosperity offers a complete line of services including: Internet Banking services at www.prosperitybankusa.com, Retail Brokerage Services, Credit Cards, MasterMoney Debit Cards, 24 hour voice response banking, Trust and Wealth Management, Mortgage Services, Cash Management and Mobile Banking.

As of June 30, 2017, Prosperity operated 243 full-service banking locations: 65 in the Houston area, including The Woodlands; 29 in the South Texas area including Corpus Christi and Victoria; 34 in the Dallas/Fort Worth area; 22 in the East Texas area; 29 in the Central Texas area including Austin and San Antonio; 34 in the West Texas area including Lubbock, Midland-Odessa and Abilene; 16 in the Bryan/College Station area, 6 in the Central Oklahoma area and 8 in the Tulsa, Oklahoma area.

“Safe Harbor” Statement under the Private Securities Litigation Reform Act of 1995: This release contains, and the remarks by Prosperity’s management on the conference call may contain, forward-looking statements within the meaning of the securities laws. Forward-looking statements include all statements other than statements of historical fact, including forecasts or trends, and are based on current expectations, assumptions, estimates and projections about Prosperity Bancshares and its subsidiaries.  These forward-looking statements are not guarantees of future performance and are subject to risks and uncertainties, many of which are outside of Prosperity’s control, which may cause actual results to differ materially from those expressed or implied by the forward-looking statements.  These risks and uncertainties include but are not limited to whether Prosperity can: successfully identify acquisition targets and integrate the businesses of acquired companies and banks; continue to sustain its current internal growth rate or total growth rate; provide products and services that appeal to its customers; continue to have access to debt and equity capital markets; and achieve its sales objectives.  Other risks include, but are not limited to: the possibility that credit quality could deteriorate; actions of competitors; changes in laws and regulations (including changes in governmental interpretations of regulations and changes in accounting standards); a deterioration or downgrade in the credit quality and credit agency ratings of the securities in Prosperity’s securities portfolio; customer and consumer demand, including customer and consumer response to marketing; effectiveness of spending, investments or programs; fluctuations in the cost and availability of supply chain resources; economic conditions, including currency rate, interest rate and commodity price fluctuations; and weather.  These and various other factors are discussed in Prosperity Bancshares’ Annual Report on Form 10-K for the year ended December 31, 2016 and other reports and statements Prosperity Bancshares has filed with the SEC. Copies of the SEC filings for Prosperity Bancshares may be downloaded from the Internet at no charge from http://www.prosperitybankusa.com.

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Prosperity Bancshares, Inc.^®

Financial Highlights (Unaudited)

(In thousands)

(A) Includes $2,871, $2,200, $2,171, $2,310 and $2,496 in unrealized gains on available for sale securities for the quarterly periods ended June 30, 2017, March 31, 2017, December 31, 2016, September 30, 2016 and June 30, 2016, respectively.

(B) Includes $1,866, $1,430, $1,411, $1,502 and $1,623 in after-tax unrealized gains on available for sale securities for the quarterly periods ended June 30, 2017, March 31, 2017, December 31, 2016, September 30, 2016 and June 30, 2016, respectively.

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Prosperity Bancshares, Inc.^®

Financial Highlights (Unaudited)

(In thousands)

(C) Interest income on securities was reduced by net premium amortization of $9,403, $9,883, $11,502, $11,312 and $10,407 for the three-month periods ended June 30, 2017, March 31, 2017, December 31, 2016, September 30, 2016 and June 30, 2016, respectively, and $19,286 and $20,660 for the six-month periods ended June 30, 2017 and June 30, 2016.

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Prosperity Bancshares, Inc. ^®

Financial Highlights (Unaudited)

(Dollars and share amounts in thousands, except per share data and market prices)

(D) Includes purchase accounting adjustments for the periods presented as follows:

(E) Using effective tax rate of 32.0%, 33.1%, 32.7%, 32.9% and 33.1% for the three-month periods ended June 30, 2017, March 31, 2017, December 31, 2016, September 30, 2016 and June 30, 2016, respectively and 32.6% and 32.9% for the six-month periods ended June 30, 2017 and June 30, 2016, respectively.

(F) Interim periods annualized.

(G) Refer to the "Notes to Selected Financial Data" at the end of this Earnings Release for a reconciliation of this non-GAAP financial measure.

(H) Net interest margin for all periods presented is based on average balances on an actual 365 day or 366 day basis.

(I) Calculated by dividing total noninterest expense, excluding credit loss provisions, by net interest income plus noninterest income, excluding net gains and losses on the sale of assets and securities.  Additionally, taxes are not part of this calculation.

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Prosperity Bancshares, Inc.^®

Financial Highlights (Unaudited)

(Dollars in thousands)