Exhibit 99.1

Rex Energy Reports Third Quarter 2017 Financial and Operational Results

STATE COLLEGE, PA., November 14, 2017 (GLOBE NEWSWIRE) – Rex Energy Corporation (Nasdaq: REXX) today announced its third quarter 2017 financial and operational results.

“The third quarter of 2017 was a very busy quarter for Rex Energy, as we are nearing an inflection point for our projected production and EBITDAX growth going into 4Q17,” said Tom Stabley, President and Chief Executive Officer. “During the quarter, we saw full utilization of our Gulf Coast transportation and improved liquids pricing, leading to strong realizations for both natural gas and C3+ production streams, a trend we see continuing. Finally, with the continued high level of operational activity during the fourth quarter, we anticipate that production in our Butler Operated Area will continue to grow and allow us to reach our targeted exit rates.”

Operational Update

Legacy Butler Operated Area

In the Legacy Butler Operated Area, the company placed into sales the four-well Wilson pad. The four wells were drilled to an average lateral length of approximately 9,300 feet and were completed in an average of 51 stages. The four wells produced at an initial 24-hour average sales rate per well of 10.9 MMcfe/d, consisting of 6.9 MMcf/d of natural gas and 721 bbls/d of NGLs. The four wells have a lower BTU rate than other areas of the Legacy Butler Operated Area, but the timing of these wells being placed into sales and the extended lateral lengths are expected to yield strong returns in the current natural gas price environment.

Moraine East Area

In the Moraine East Area, the company drilled four gross (four net) wells, completed six gross (3.4 net) wells and placed into sales twelve gross (6.5 net) wells in the third quarter of 2017. In addition, the company had seven gross (5.5 net) wells awaiting completion at the end of the third quarter.

As previously reported, the company placed the two-well Frye pad into sales during the third quarter. The two wells produced at an average 24-hour sales rate per well, assuming full ethane recovery, of 9.4 MMcfe/d. The two wells have gone on to produce at an average 30-day sales rate per well of 8.5 MMcfe/d, consisting of 3.7 MMcf/d of natural gas, 747 bbls/d of NGLs and 48 bbls/d of condensate. The two Frye wells were completed using the company’s optimized completion design, continue their strong performance to date. Comparing the two Frye wells to their expected type curve, both wells are currently outperforming their respective type curves.

The company finished completing the three-well Manuel pad, which was drilled to an average lateral length of approximately 6,750 feet and completed in an average of 41 stages. The three wells are expected to be placed into sales in early December 2017.

Warrior North Area

In the Warrior North Area, the company has begun completing the three-well Jenkins pad. The three wells were drilled to an average lateral length of approximately 6,500 feet. The wells are expected to be completed at the end of the fourth quarter of 2017 and placed into sales in January 2018. The three existing wells on the Jenkins pad, which account for approximately 2.6 MMcfe/d of production, will be shut in during the completion and initial flow back of the three new Jenkins wells.

In addition, the company began drilling the seven-well Goebeler pad and is currently drilling the fifth of seven wells on the pad. The seven wells are expected to be drilled to an average lateral length of approximately 7,500 feet and placed into sales in the second quarter of 2018.

The combination of the three-well Jenkins pad and seven-well Goebeler pad will be the primary driver for the company’s 2018 condensate growth rate of 150% - 175%.

Third Quarter Financial Results

Commodity revenues, including settlements from derivatives, for the three and nine months ended September 30, 2017 were $46.6 million and $140.6 million, respectively, which represents an increase of 29% and 14% over the same periods in 2016. Commodity revenues from natural gas liquids (NGLs) and condensate, including settlements from derivatives, represented 41% of total commodity revenues for the three months ended September 30, 2017.

Lease operating expense (LOE) from continuing operations was $30.6 million, or $1.83 per Mcfe for the third quarter. For the nine months ended September 30, 2017, LOE was approximately $88.9 million, or $1.83 per Mcfe. General and administrative (G&A) expenses from continuing operations were $4.6 million for the third quarter of 2017, or $0.28 per Mcfe. For the nine months ended September 30, 2017, G&A expenses from continuing operations were $13.4 million, or $0.28 per Mcfe. Cash G&A expenses from continuing operations (a non-GAAP measure) for the three months ended September 30, 2017 were $4.2 million, or $0.25 per Mcfe. For the nine months ended September 30, 2017, cash G&A expenses from continuing operations (a non-GAAP measure) were $12.5 million, or $0.26 per Mcfe. The company expects substantial reductions, on a per unit basis, for LOE in the fourth quarter of 2017.

Net loss attributable to common shareholders for the three months ended September 30, 2017 was $47.1 million, or $4.76 per basic share. Net loss attributable to common shareholders for the nine months ended September 30, 2017 was $55.2 million, or $5.60 per basic share. Adjusted net loss, a non-GAAP measure, for the three months ended September 30, 2017 was $9.9 million, or $1.00 per share. Adjusted net loss for the nine months ended September 30, 2017 was $24.6 million, or $2.50 per share.

EBITDAX from continuing operations, a non-GAAP measure, was $11.9 million for the third quarter of 2017 and $39.9 million for the nine months ended September 30, 2017, representing increases of 163% and 25% over the same periods in 2016, respectively.

Reconciliations of adjusted net loss to GAAP net loss, EBITDAX to GAAP net loss and G&A to cash G&A for the three and nine months ended September 30, 2017, as well as a discussion of the uses of each measure, are presented in the appendix of this release.

Production Results and Price Realizations

Third quarter 2017 production volumes from continuing operations were 182.0 MMcfe/d, consisting of 112.0 MMcf/d of natural gas, 5.1 Mbbls/d of C3+ NGLs, 6.0 Mbbls/d of ethane and 0.7 Mbbls/d of condensate. NGLs (including ethane) and condensate accounted for 38% of net production for the third quarter of 2017. The company exceeded production guidance through strong operating efficiencies which allowed for earlier turn inline dates for the Shields and Mackrell pads in the Moraine East Area.

Including the effects of cash-settled derivatives, realized prices for the three months ended September 30, 2017 were $2.66 per Mcf for natural gas, $23.44 per barrel for C3+ NGLs, $10.14 per barrel for ethane and $44.47 per barrel for condensate. Before the effects of hedging, realized prices for the three months ended September 30, 2017 were $2.52 per Mcf for natural gas, $29.62 per barrel for C3+ NGLs, $10.28 per barrel for ethane and $42.00 per barrel for condensate.

Including the effects of cash-settled derivatives, realized prices for the nine months ended September 30, 2017 were $2.83 per Mcf for natural gas, $23.40 per barrel for C3+ NGLs, $9.95 per barrel for ethane and $45.02 per barrel for condensate. Before the effects of hedging, realized prices for the nine months ended September 30, 2017 were $2.87 per Mcf for natural gas, $27.82 per barrel for C3+ NGLs, $9.93 per barrel for ethane and $43.58 per barrel for condensate.

Third Quarter 2017 Capital Investments

For the third quarter of 2017, net operational capital investments were approximately $25.1 million. The company expects to be reimbursed by joint development partners for approximately $5.9 million of previously incurred costs that were not billed until the fourth quarter of 2017. Capital investments in the third quarter of 2017 funded the drilling of seven gross (seven net) wells, fracture stimulation of six gross (3.4 net) wells and other projects related to drilling and completing wells in the Appalachian Basin. Net operated capital expenditures for the full-year 2017 are still expected to be within the range of the company’s previously issued guidance of $115.0 million - $130.0 million.

Liquidity Update

As of September 30, 2017, the company had approximately $3.2 million of cash on hand and outstanding borrowings under its term loan credit agreement of approximately $155.5 million with an additional $32.2 of undrawn letters of credit outstanding. As of September 30, 2017, the company had approximately $112.3 million of undrawn availability under its tern loan credit agreement.

Fourth Quarter and Full Year 2017 Guidance

Rex Energy is providing guidance for the fourth quarter of 2017 and maintaining its full-year 2017 guidance ($ in millions). The company’s fourth quarter 2017 production guidance accounts for the approximately 2.6 MMcfe/d of production shut-in due to the completion and initial flowback of the three-well Jenkins pad in Warrior North. In addition, the company is maintaining its year-end 2017 exit rate production growth rate guidance of 15% - 20% upon the commissioning of its fourth compressor in the Moraine East Area.

Conference Call Information

Management will host a live conference call and webcast on Wednesday, November 15, 2017 at 10:00 a.m. Eastern to review third quarter 2017 financial results and operational highlights. The telephone number to access the conference call is (866) 437-1772.

About Rex Energy Corporation

Headquartered in State College, Pennsylvania, Rex Energy is an independent oil and gas exploration and production company with its core operations in the Appalachian Basin. The company’s strategy is to pursue its higher potential exploration drilling prospects while acquiring oil and natural gas properties complementary to its portfolio.

Forward-Looking Statements

Except for historical information, all statements made in this release, including those relating to the timing and nature of development plans; drilling and completion schedules; anticipated fracture stimulation activities; expected dates for placement of wells into sales; and our financial guidance for fourth quarter and full year 2017 are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. Forward-looking statements may contain words such as “expected”, “expects”, “scheduled”, “planned”, “plans”, “anticipates” or similar words, and are based on management’s experience and perception of historical trends, current conditions, and anticipated future developments, as well as other factors believed to be appropriate. We believe these statements and the assumptions and estimates contained in this release are reasonable based on information that is currently available to us. However, management’s assumptions and the company’s future performance are subject to a wide range of business risks and uncertainties, both known and unknown, and we cannot assure that the company can or will meet the goals,

expectations, and projections included in this release. Any number of factors could cause our actual results to be materially different from those expressed or implied in our forward looking statements, including (without limitation):

We undertake no obligation to publicly update or revise any forward-looking statements. Further information on the company’s risks and uncertainties is available in our filings with the Securities and Exchange Commission and we strongly encourage investors to review those filings.

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For more information contact:

Investor Relations

(814) 278-7130

InvestorRelations@rexenergycorp.com

REX ENERGY CORPORATION

CONSOLIDATED BALANCE SHEETS

($ in Thousands, Except Share and Per Share Data)

REX ENERGY CORPORATION

CONSOLIDATED STATEMENTS OF OPERATIONS

(Unaudited, in Thousands, Except per Share Data)

REX ENERGY CORPORATION

CONSOLIDATED OPERATIONAL HIGHLIGHTS

REX ENERGY CORPORATION

COMMODITY DERIVATIVES – HEDGE POSITION AS OF 11/10/2017

APPENDIX

REX ENERGY CORPORATION

NON-GAAP MEASURES

EBITDAX

“EBITDAX” means, for any period, the sum of net income for such period plus the following expenses, charges or income to the extent deducted from or added to net income in such period: interest, income taxes, DD&A, unrealized losses from financial derivatives, non-recurring gains and losses, exploration expenses and other similar non-cash charges, minus all non-cash income, including but not limited to, income from unrealized financial derivatives and gains on asset dispositions, added to net income. EBITDAX, as defined above, is used as a financial measure by our management team and by other users of its financial statements, such as our commercial bank lenders to analyze such things as:

EBITDAX is not a calculation based on GAAP financial measures and should not be considered as an alternative to net income (loss) (the most directly comparable GAAP financial measure) in measuring our performance, nor should it be used as an exclusive measure of cash flows, because it does not consider the impact of working capital growth, capital expenditures, debt principal reductions, and other sources and uses of cash, which are disclosed in our consolidated statements of cash flows.

We have reported EBITDAX because it is a financial measure used by our existing commercial lenders, and because this measure is commonly reported and widely used by investors as an indicator of a company’s operating performance and ability to incur and service debt. You should carefully consider the specific items included in our computations of EBITDAX. While we have disclosed EBITDAX to permit a more complete comparative analysis of our operating performance and debt servicing ability relative to other companies, you are cautioned that EBITDAX as reported by us may not be comparable in all instances to EBITDAX as reported by other companies. EBITDAX amounts may not be fully available for management’s discretionary use, due to requirements to conserve funds for capital expenditures, debt service and other commitments.

We believe that EBITDAX assists our lenders and investors in comparing our performance on a consistent basis without regard to certain expenses, which can vary significantly depending upon accounting methods. Because we may borrow money to finance our operations, interest expense is a necessary element of our costs. In addition, because we use capital assets, DD&A are also necessary elements of our costs. Finally, we are required to pay federal and state taxes, which are necessary elements of our costs. Therefore, any measures that exclude these elements have material limitations.

To compensate for these limitations, we believe it is important to consider both net income determined under GAAP and EBITDAX to evaluate our performance.

For purposes of consistency with current calculations, we have revised certain amounts relating to prior period EBITDAX. The following table presents a reconciliation of our net income to EBITDAX for each of the periods presented.

Adjusted Net Loss

“Adjusted Net Loss” means, for any period, the sum of net income (loss) from continuing operations before income taxes for the period plus the following expenses, charges or income, in each case, to the extent deducted from or added to net income in the period: unrealized losses from financial derivatives, non-cash compensation expense, dry hole expenses, disposals of assets, impairment and other one-time or non-recurring charges, minus all gains from unrealized financial derivatives, disposal of assets and deferred income tax benefits, added to net income. Adjusted Net Loss is used as a financial measure by Rex Energy’s management team and by other users of its financial statements, to analyze its financial performance without regard to non-cash deferred taxes and non-cash unrealized losses or gains from oil and gas derivatives. Adjusted Net Loss is not a calculation based on GAAP financial measures and should not be considered as an alternative to net income (loss) in measuring the company’s performance.

Rex Energy reports Adjusted Net Loss because it believes that this measure is commonly reported and widely used by investors as an indicator of a company’s operating performance. You should carefully consider the specific items included in the company’s computation of this measure. You are cautioned that Adjusted Net Income as reported by Rex Energy may not be comparable in all instances to that reported by other companies.

To compensate for these limitations, the company believes it is important to consider both net income determined under GAAP and Adjusted Net Income.

The following table presents a reconciliation of Rex Energy’s net income from continuing operations to its adjusted net loss for each of the periods presented ($ in thousands):

Cash General and Administrative Expenses

Cash General and Administrative Expenses (Cash G&A) is the difference between GAAP G&A and non-Cash G&A, which is primarily comprised of non-cash compensation expense. Rex Energy has reported Cash G&A because it believes that this measure is commonly reported and widely used by management and investors as an indicator of overhead efficiency without regard to non-cash expenditures, such as stock compensation. Cash G&A is not a calculation based on GAAP financial measures and should not be considered as an alternative to GAAP G&A in measuring the company’s performance. You should carefully consider the specific items included in the company’s computation of this measure. You are cautioned that Cash G&A as reported by Rex Energy may not be comparable in all instances to that reported by other companies.

To compensate for these limitations, the company believes it is important to consider both Cash G&A and GAAP G&A. The following table presents a reconciliation of Rex Energy’s GAAP G&A to its Cash G&A for each of the periods presented (in thousands):