Exhibit 99.1

Mercantile Bank Corporation Reports Strong Fourth Quarter and

Full Year 2012 Results

Improved asset quality and earnings performance, and positive outlook mark 15-year anniversary

GRAND RAPIDS, Mich., January 15, 2013 – Mercantile Bank Corporation (NASDAQ: MBWM) (“Mercantile”) reported net income attributable to common shares of $3.0 million, or $0.35 per diluted share, for the fourth quarter of 2012, compared with net income attributable to common shares of $30.0 million, or $3.37 per diluted share, for the prior-year period. For the full year 2012, Mercantile reported net income attributable to common shares of $11.5 million, or $1.30 per diluted share, compared with net income attributable to common shares of $36.1 million, or $4.07 per diluted share, for the full year 2011.

During the fourth quarter of 2011, net income attributable to common shares was positively impacted by the reversal of the previously established net deferred tax asset valuation allowance resulting in a federal income tax benefit of $27.4 million. On a pre-tax basis, 2012 income was $4.3 million in the fourth quarter and $18.2 million for the full year, compared to 2011 income of $3.0 million in the fourth quarter and $10.1 million for the full year.

2012 was highlighted by:

“2012 marked the 15^th anniversary of Mercantile Bank, and we are very pleased to recognize this milestone during a year filled with many successes and accomplishments,” said Michael Price, Chairman and CEO of Mercantile. “Throughout the year, we remained focused on improving asset quality, increasing core profitability, protecting our net interest margin and further strengthening our balance sheet. Because of our success in all these areas, we exited the TARP Program by repurchasing our preferred stock and common stock warrant entirely with internally-generated funds, and reinstated our quarterly cash dividend. As a result of our strengthened position, we feel very confident about the opportunities available to us in the coming year.”

Operating Results

Total revenue, which consists of net interest income and noninterest income, was $13.8 million during the fourth quarter of 2012, down $0.6 million or 3.9 percent from the $14.4 million generated during the prior-year fourth quarter. Total revenue was $54.7 million during the full year 2012, down $3.8 million or 6.5 percent from the $58.5 million generated during 2011. The declines in total revenue during the 2012 periods compared to the 2011 periods resulted from decreased net interest income. Net interest income during the fourth quarter of 2012 was $11.7 million, down $0.6 million or 4.8 percent from the fourth quarter of 2011, reflecting a 4.3 percent decrease in average earning assets and a slight decline in the net interest margin. Net interest income was $46.7 million in 2012, down $4.5 million or 8.9 percent from the $51.2 million earned in the prior year, reflecting a 10.7 percent decrease in average earning assets, which was partially offset by an increased net interest margin. The reduction in average earning assets in the 2012 periods compared to the respective 2011 periods primarily resulted from the continuation of management’s strategic initiative to reduce commercial real estate exposure and migrate certain high risk loans out of the loan portfolio. The net interest margin during 2012 was 3.67 percent, up from 3.60 percent during 2011 and well above the historical average level.

Noninterest income during the fourth quarter of 2012 was $2.1 million, up slightly from $2.0 million during the prior-year fourth quarter. Noninterest income for 2012 was $8.0 million, up $0.7 million or 9.8 percent from 2011. The increase in noninterest income during the 2012 periods compared to the respective 2011 periods primarily resulted from higher residential mortgage banking fee income and rental income on foreclosed properties.

Provision expense was $0.3 million in the fourth quarter of 2012 compared to $1.9 million in the fourth quarter of 2011. Mercantile recorded a negative $3.1 million provision for loan losses during 2012 compared to a provision expense of $6.9 million for 2011. The negative provision expense is the result of several factors, including continued progress towards loan recoveries and collections as well as a reduced level of loan-rating downgrades and ongoing loan-rating upgrades.

Noninterest expense totaled $9.2 million during the fourth quarter of 2012, down $0.3 million or 3.3 percent from the prior-year fourth quarter. Noninterest expense for 2012 was $39.6 million, down $1.9 million or 4.5 percent from 2011. Salaries and benefits totaled

$5.0 million during the fourth quarter of 2012 and $19.4 million during 2012, up $0.5 million and $1.5 million from the respective 2011 periods. The increased salary and benefit costs primarily reflect expense associated with reinstating certain employee benefit programs that had been suspended or reduced in prior years. Costs associated with the administration and resolution of problem assets, including legal expenses, property tax payments, appraisal costs and write-downs on foreclosed properties, totaled $0.9 million during the fourth quarter of 2012, down $0.7 million or 43.7 percent from the $1.6 million expensed during the fourth quarter of 2011, and $5.9 million during 2012, down $2.4 million or 29.3 percent from the $8.3 million expensed during 2011. The reduction in nonperforming asset costs reflects the continuation of Mercantile’s aggressive approach to managing and resolving problem assets. Federal Deposit Insurance Corporation (“FDIC”) insurance premiums were $0.3 million during the current-year fourth quarter, down $0.3 million or 46.2 percent from the 2011 fourth quarter, and $1.2 million in 2012, down $1.6 million or 57.8 percent from 2011. The decreased FDIC insurance premiums primarily resulted from a lower assessment rate that reflects Mercantile’s improved financial condition and operating performance.

Mr. Price continued: “Our fourth quarter financial results cap another full year of impressive performance for Mercantile, and provide strong momentum for 2013. Our improved financial condition and strong capital position have added to our ability to be flexible and opportunistic as we pursue disciplined growth for long-term performance.”

Balance Sheet

As of December 31, 2012, total assets were $1.42 billion, down $10.3 million or 0.7 percent from December 31, 2011; total loans decreased $31.2 million, or 2.9 percent, to $1.04 billion over the same period. While efforts to reduce certain segments of the commercial real estate portfolio continue, total loans increased $5.9 million during the fourth quarter of 2012. Continued relationship building efforts have led to increased lending opportunities, and despite competitive pressures, $63.8 million in loans to existing and new borrowers were originated in the fourth quarter of 2012 and $176 million were originated during the full year of 2012.

Real estate loans comprise a majority of Mercantile’s loan portfolio. At December 31, 2012, real estate loans, excluding residential mortgage loans representing permanent financing of owner-occupied dwellings and home equity lines of credit, were $677 million or approximately 65 percent of total loans, representing a decline of $45.9 million, or 6.3 percent, from $723 million, or 67.4 percent of total loans, at December 31, 2011.

Non-owner-occupied commercial real estate (“CRE”) loans totaled $354 million as of December 31, 2012 (34.0 percent of total loans), a decline of $22.7 million over the past 12 months. Owner-occupied CRE loans were $262 million at the end of 2012, a decrease of $6.4 million from a year ago. Vacant land, land development and construction (“C&D”) loans, including both residential and commercial projects, totaled $55.2 million at December 31, 2012, down $15.3 million from a year ago. The commercial and industrial (“C&I”) segment of the loan portfolio was $285 million at December 31, 2012, an increase of approximately $18 million since year-end 2011. The average balance of commercial lines of credit has remained relatively stable since early 2011.

LOANS SECURED BY REAL ESTATE

Since December 2008, Mercantile has focused on improving liquidity by reducing wholesale funding and growing local deposits, especially interest-bearing checking and money market deposit accounts. As of December 31, 2012, total deposits were $1.14 billion, a decline of $464 million since year-end 2008. By comparison, local deposits increased $395 million to $866 million since year-end 2008, representing 76.2 percent of total deposits compared to 29.4 percent at December 31, 2008. Approximately 65 percent, or $258 million, of local deposit growth since year-end 2008 occurred in the interest-bearing checking and money market deposit account categories, while DDA checking accounted for $79.5 million, or about 20 percent of total growth. Growth in local deposits was driven primarily by the introduction of innovative new products, various deposit-gathering initiatives, enhanced advertising and branding campaigns, and transfers from maturing time deposit accounts.

Wholesale funds were $305 million, or 24.7 percent of total funds, as of December 31, 2012, compared to $1.41 billion, or 71.5 percent of total funds, as of December 31, 2008. The $1.11 billion decline in wholesale funding since the end of 2008 reflects both the shift toward local deposits, as well as an $816 million decline in total loans. This strategy has allowed Mercantile to reduce brokered deposits and Federal Home Loan Bank advances as they matured since year-end 2008.

Short-term investments, consisting of federal funds sold and interest-bearing bank deposits, averaged $129 million during the fourth quarter of 2012. In addition to its short-term investments, Mercantile had approximately $155 million of borrowing capacity through various established lines of credit to meet potential funding needs, as well as about $37 million of U.S. Government securities available to sell, as of December 31, 2012.

Asset Quality

Nonperforming assets (“NPAs”) at December 31, 2012 were $25.9 million, or 1.8 percent of total assets, compared to $60.4 million as of December 31, 2011, or 4.2 percent of total assets. This represents a decline of $34.5 million or 57.0 percent from the end of 2011.

Robert B. Kaminski, Jr., Mercantile’s Executive Vice President and Chief Operating Officer, noted: “We are very pleased with our efforts to improve asset quality and believe the actions taken throughout 2012 and especially during the fourth quarter, continue to reflect our aggressive stance to move troubled assets off our balance sheet. Our nonperforming assets now represent less than two percent of our total assets – a level we haven’t witnessed since early 2008, and our 30-to 89-day delinquent loans remain virtually at zero. We believe our results compare favorably when judged against those of other recovering Midwest and Michigan banks. While there remains work yet to be done, we feel strongly that many of the challenges from the past several years are now behind us. We continue to be grateful to the entire Mercantile team for all their hard work on this initiative, while staying true to our community banking roots and maintaining a steady focus on meeting the needs of our existing customers and driving the growth of new relationships in our market. Mercantile is well-positioned for growth, and while the market remains competitive, we are benefiting from our robust sales programs and marketing initiatives as evidenced by the $64 million in new loans we originated in the fourth quarter and the $176 million originated during all of 2012.”

Nonperforming loans (“NPLs”) totaled $19.0 million as of December 31, 2012, down $26.1 million from a year ago, while foreclosed real estate and repossessed assets declined $8.3 million from December 31, 2011. CRE loans represented 61.5 percent of NPLs, or $11.7 million at December 31, 2012. Investor-owned nonperforming CRE loans accounted for $9.1 million of total CRE nonperforming loans (2.6 percent of $354 million investor-owned CRE loans), while owner-occupied CRE nonperforming loans accounted for $2.6 million (1.0 percent of $262 million owner-occupied CRE loans).

Nonperforming C&D loans were $2.2 million as of December 31, 2012, a decrease of $1.7 million from a year ago. Nonperforming C&I loans were $0.7 million as of December 31, 2012, a decline of $2.3 million since December 31, 2011. Owner-occupied and rental residential NPLs were $4.3 million as of December 31, 2012, down $1.7 million since year-end 2011.

NONPERFORMING ASSETS

During the fourth quarter of 2012, Mercantile added $3.7 million of NPAs to its problem asset portfolio, while disposing of $13.7 million through a combination of principal payments, asset sales and returns to performing status ($11.9 million), loan charge-offs ($1.2 million), and foreclosed asset valuation write-downs ($0.6 million). In total, NPAs decreased by a net $10.0 million during the fourth quarter of 2012.

Improvement in asset quality is also apparent on a full-year basis. During the 12-month period ended December 31, 2012, Mercantile added $16.8 million of problem assets to its NPA portfolio, successfully disposed of $42.8 million, and charged off or wrote down an additional $8.4 million. In total, NPAs declined by a net $34.4 million since December 31, 2011.

NONPERFORMING ASSETS RECONCILIATION

Net loan recoveries were $0.6 million during the fourth quarter of 2012, or an annualized negative 0.2 percent of average loans, compared with net loan charge-offs of $1.5 million (0.6 percent annualized) and net loan charge-offs of $4.7 million (1.8 percent annualized) for the linked and prior-year quarters, respectively.

NET LOAN CHARGE-OFFS (RECOVERIES)

Capital Position

Shareholders’ equity totaled $147 million as of December 31, 2012, a decrease of $18.4 million from December 31, 2011. During the second quarter of 2012, Mercantile repurchased the entire $21.0 million of preferred stock that was sold to the U.S. Department of the Treasury on May 15, 2009. On July 3, 2012 Mercantile repurchased, for $7.5 million, the warrant it sold to the U.S. Department of the Treasury on May 15, 2009. The warrant provided for the purchase of 616,438 shares of Mercantile common stock at a price of $5.11 per share. To fund the repurchases, the Bank paid cash dividends to the Company in approximately the same amounts. The Bank remains “well-capitalized” with a total risk-based capital ratio of 14.7 percent as of December 31, 2012, compared to 15.5 percent at December 31, 2011. At December 31, 2012, the Bank had approximately $55.5 million in excess of the 10.0 percent minimum regulatory threshold required to be considered a “well-capitalized” institution. Mercantile reported 8,706,251 total shares outstanding at December 31, 2012.

With the continued strength of Mercantile’s operating performance and capital position, on January 10, 2013, the Board of Directors declared a cash dividend of $0.10 per common share, which is payable in the first quarter of 2013. The $0.10 cash dividend represents an increase of 11 percent from the $0.09 cash dividend paid to common shareholders during the fourth quarter of 2012.

Mr. Price concluded: “We have come a long way on our 15-year journey, and we have grown steadily through lessons learned along the way. We have emerged from the Great Recession a stronger and more efficient organization. Armed with improved financial performance, a strong capital position and sustained earnings momentum, we are optimistic about the next stage on our Company’s path towards disciplined growth and increasing value for our shareholders.”

About Mercantile Bank Corporation

Based in Grand Rapids, Michigan, Mercantile Bank Corporation is the bank holding company for Mercantile Bank of Michigan. Founded in 1997 to provide banking services to businesses, individuals and governmental units, the Bank differentiates itself on the basis of service quality and the expertise of its banking staff. Mercantile has seven full-service banking offices in Grand Rapids, Holland and Lansing, Michigan. Mercantile Bank Corporation’s common stock is listed on the NASDAQ Global Select Market under the symbol “MBWM.”

Forward-Looking Statements

This news release contains comments or information that constitute forward-looking statements (within the meaning of the Private Securities Litigation Reform Act of 1995) that are based on current expectations that involve a number of risks and uncertainties. Actual results may differ materially from the results expressed in forward-looking statements. Factors that might cause such a difference include changes in interest rates and interest rate relationships; demand for products and services; the degree of competition by traditional and nontraditional competitors; changes in banking regulation or actions by bank regulators; changes in tax laws; changes in prices, levies, and assessments; the impact of technological advances; governmental and regulatory policy changes; the outcomes of contingencies; trends in customer behavior as well as their ability to repay loans; changes in local real estate values; changes in the national and local economies; and other factors, including risk factors, disclosed from time to time in filings made by Mercantile with the Securities and Exchange Commission. Mercantile undertakes no obligation to update or clarify forward-looking statements, whether as a result of new information, future events or otherwise.

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Fourth Quarter 2012 Results

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CONSOLIDATED BALANCE SHEETS

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Fourth Quarter 2012 Results

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CONSOLIDATED REPORTS OF OPERATIONS

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Fourth Quarter 2012 Results

MERCANTILE BANK CORPORATION

CONSOLIDATED FINANCIAL HIGHLIGHTS

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