Exhibit 99.1

For Immediate Release

Investar Holding Corporation Announces 2015 Third Quarter Results

BATON ROUGE, LA (October 27, 2015) – Investar Holding Corporation (NASDAQ: ISTR) (the “Company”), the holding company for Investar Bank (the “Bank”), today announced financial results for the quarter ended September 30, 2015. For the quarter ended September 30, 2015, the Company reported net income of $1.8 million, or $0.26 per diluted share, compared to $1.8 million, or $0.25 per diluted share, for the quarter ended June 30, 2015, and $1.4 million, or $0.20 per diluted share, for the quarter ended September 30, 2014. This represents an increase of $0.4 million, or 28.7%, in net income for the quarter ended September 30, 2015 when compared to the same quarter in 2014.

Core earnings, a non-GAAP measure which excludes the after-tax impact of securities gains and losses, gains and losses on the sale of other real estate owned, and other identified costs recorded for the period, were $1.9 million, or $0.26 per diluted share, for the quarter ended September 30, 2015 compared to core earnings of $1.2 million, or $0.16 per diluted share, for the quarter ended September 30, 2014. See calculation of core earnings on the Reconciliation of Non-GAAP Financial Measures .

Investar Holding Corporation President and Chief Executive Officer John D’Angelo said:

“We are pleased to announce another great quarter for Investar. We continue to experience solid loan growth throughout our markets. C&I loan growth remains a focus and we are pleased with the 25% year to date growth in the portfolio. We are also continuing to see the results of our efforts to grow our noninterest-bearing deposits with 35% growth year to date.

We remain aligned with our shareholders and are focused on enhancing the value of our franchise. We believe this will be achieved by transitioning the Bank to a more relationship-based model from a transaction-oriented one. We are committed to investing resources in developing and growing our small business banking strategy.”

Third Quarter Highlights

Consumer loans, including consumer loans held for sale, totaled $175.7 million at September 30, 2015, a decrease of $38.3 million, or 17.9%, from $214 million at December 31, 2014. The decrease is mainly attributable to the $46.4 million decrease in the balance of consumer loans held for sale at September 30, 2015 when compared to December 31, 2014. Two consumer loan sales were postponed by the buyer from the fourth quarter of 2014 to the first quarter of 2015, therefore increasing the balance of consumer loans held for sale at December 31, 2014.

At September 30, 2015, the Company’s total business lending portfolio, which consists of loans secured by owner occupied commercial real estate properties and commercial and industrial loans, was $200.1 million, an increase of $26.2 million, or 15.1%, compared to the business lending portfolio of $173.9 million at December 31, 2014.

Management continues to monitor the Company’s loan portfolio for exposure, directly or indirectly, to the potential negative impacts from the decline in oil and gas prices. Less than 1% of the total loan portfolio remains directly related to the energy sector. At this time, management does not anticipate that oil and gas prices at current levels will negatively impact borrowers’ ability to service their debt.

The provision for loan loss expense was $0.4 million for the third quarter of 2015, a decrease of $0.1 million compared to the third quarter of 2014. The allowance for loan losses was $5.9 million, or 226.43% and 0.83% of nonperforming loans and total loans, respectively, at September 30, 2015, compared to $4.6 million, or 138.61% and 0.74% of nonperforming loans and total loans, respectively, at December 31, 2014. The allowance for loan losses plus the fair value marks on acquired loans was 0.93% of total loans at September 30, 2015 compared to 0.88% at December 31, 2014. Nonperforming loans to total loans improved to 0.37% at September 30, 2015 compared to 0.54% at December 31, 2014.

Deposits

Total deposits at September 30, 2015 were $730.4 million, an increase of $102.3 million, or 16.3%, from December 31, 2014. The increase in total deposits was driven primarily by an increase of $24.3 million, or 34.6%, in noninterest-bearing demand deposits, and an increase in time deposits of $43.5 million, or 14%, from December 31, 2014. The Company’s focus on relationship banking, including our deposit cross sell strategy, as well as management’s focus on growing the commercial and industrial loan portfolio and bringing in related deposits, continues to positively impact both noninterest-bearing demand deposit and NOW account growth.

The following table sets forth the composition of the Company’s deposits as of the dates indicated (dollars in thousands).

Net Interest Income

Net interest income for the third quarter of 2015 totaled $8 million, an increase of $0.2 million, or 2.2%, compared to the second quarter of 2015, and an increase of $1 million, or 13.6%, compared to the third quarter of 2014. The increase was a direct result of continued growth of the Company’s loan portfolio with an increase in net interest income of $1.8 million due to an increase in volume offset by a $0.8 million decrease related to a reduction in yield compared to the third quarter of 2014.

The Company’s net interest margin was 3.52% for the quarter ended September 30, 2015 compared to 3.70% for the second quarter of 2015 and 3.86% for the third quarter of 2014. The yield on interest-earning assets was 4.20% for the quarter ended September 30, 2015 compared to 4.37% for the second quarter of 2015 and 4.51% for the third quarter of 2014. The decrease in both the net interest margin and yield on interest-earning assets can be attributed to the consumer loan portfolio. The consumer loan portfolio primarily consists of indirect auto loans and has experienced margin compression related to its current originations.

The cost of deposits increased one basis point when comparing the third quarter of 2015 to the second quarter of 2015, and increased three basis points when comparing the third quarter of 2015 to the third quarter of 2014.

Noninterest Income

Noninterest income for the third quarter of 2015 totaled $2.2 million, an increase of $0.1 million, or 4.9%, compared to the second quarter of 2015, and an increase of $0.2 million, or 10.6%, compared to the third quarter of 2014. The largest component of noninterest income is the gain on sale of loans, representing 47.2% and 58.7% for the third quarters of 2015 and 2014, respectively.

The following table sets forth the composition of the Company’s gain on sale of loans for the time periods indicated (dollars in thousands).

The increase in noninterest income from the third quarter of 2014 resulted primarily from the $0.3 million increase in both other operating income and gain on sale of investment securities, offset by a $0.4 million decrease in gain on sale of real estate owned, net. The increase in other operating income is mainly attributable to the $0.2 million increase in servicing fees, a direct result of the growth in the Company’s servicing portfolio from increased consumer loan sales.

Core noninterest income, which excludes the gains and losses on the sales of investment securities and other real estate owned, was $2 million for the third quarter of 2015, an increase of $0.1 million, or 2.9%, compared to $1.9 million for the second quarter of 2015, and an increase of $0.3 million, or 19.9%, compared to the third quarter of 2014.

Noninterest Expense

Noninterest expense for the third quarter of 2015 totaled $7 million, an increase of $0.3 million, or 5%, compared to the second quarter of 2015, and an increase of $0.7 million, or 11.1%, compared to the third quarter of 2014. The increase in noninterest expense from the third quarter of 2014 is primarily due to the $0.4 million increase in salaries and employee benefits and the $0.2 million increase in other operating expenses, both of which are mainly attributable to the continued growth of the Company including the opening of the Highland Road branch in Baton Rouge, Louisiana on August 1, 2014.

During the quarter, the Company incurred restructuring costs of approximately $0.3 million. These costs included severance of $150,000, which contributed to the $0.4 million increase in salaries and benefits discussed above, professional fees of $61,000, and other expenses of $105,000 related to the downsizing of our indirect lending platform. The downsizing can be attributed to the Company’s ongoing strategic shift to enhance franchise value by transitioning to a more relationship-based model from one that is transaction-oriented. The Company also recorded an impairment of $54,000 on its investment in a tax credit entity. Core noninterest expense, which excludes the impact of these costs, was $6.6 million for both the third and second quarters of 2015, an increase of $0.3 million, or 5.2%, compared to the third quarter of 2014.

Basic Earnings Per Share and Diluted Earnings Per Share

The Company reported both basic and diluted earnings per share of $0.26 for the three months ended September 30, 2015, an increase of $0.06 compared to basic and diluted earnings per share for the three months ended September 30, 2014.

Core basic and diluted earnings per share were $0.26 for the three months ended September 30, 2015, an increase of $0.09 and $0.10, respectively, compared to core basic earnings per share of $0.17 and core diluted earnings per share of $0.16 for the three months ended September 30, 2014.

Taxes

The Company recorded income tax expense of $0.9 million for the quarter ended September 30, 2015, which equates to an effective tax rate of 31.4%. During the third quarter, the Company recorded an additional tax credit related to its investment in a tax credit entity in December 2014 whose purpose was to invest in a Federal Historic Rehabilitation tax credit project. The Company recognized a tax credit of $72,000, reducing tax expense for the third quarter, as well as a corresponding impairment on its investment in the tax credit entity of $54,000.

About Investar Holding Corporation

Investar Holding Corporation, headquartered in Baton Rouge, Louisiana, provides full banking services, excluding trust services, through its wholly-owned banking subsidiary, Investar Bank, a state chartered bank. The Company’s primary market is South Louisiana and it currently operates 11 full service banking offices located throughout its market. At September 30, 2015, the Company had 165 full-time equivalent employees.

Non-GAAP Financial Measures

This press release contains financial information determined by methods other than in accordance with generally accepted accounting principles in the United States of America, or GAAP. These measures and ratios include “tangible common equity,” “tangible assets,” “tangible equity to tangible assets,” “tangible book value per common share,” “efficiency ratio,” “core noninterest income,” “core earnings before noninterest expense,” “core noninterest expense,” “core income tax expense,” “core earnings,” “core efficiency ratio,” “core return on average assets,” “core return on average equity,” “core basic earnings per share,” and “core diluted earnings per share.” Management believes these non-GAAP financial measures provide information useful to investors in understanding the Company’s financial results, and the Company believes that its presentation, together with the accompanying reconciliations, provide a more complete understanding of factors and trends affecting the Company’s business and allow investors to view performance in a manner similar to management, the entire financial services sector, bank stock analysts and bank regulators. These non-GAAP measures should not be considered a substitute for GAAP basis measures and results, and the Company 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. A reconciliation of the non-GAAP financial measures disclosed in this press release to the comparable GAAP financial measures is included at the end of the financial statement tables.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 that reflect the Company’s current views with respect to, among other things, future events and financial performance. The Company generally identifies forward-looking statements by terminology such as “outlook,” “believes,” “expects,” “potential,” “continues,” “may,” “will,” “could,” “should,” “seeks,” “approximately,” “predicts,” “intends,” “plans,” “estimates,” “anticipates,” or the negative version of those words or other comparable words. Any forward-looking statements contained in this press release are based on the historical performance of the Company and its subsidiaries or on the Company’s current plans, estimates and expectations. The inclusion of this forward-looking information should not be regarded as a representation by the Company that the future plans, estimates or expectations by the Company will be achieved. Such forward-looking statements are subject to various risks and uncertainties and assumptions relating to the Company’s operations, financial results, financial condition, business prospects, growth strategy and liquidity. If one or more of these or other risks or uncertainties materialize, or if the Company’s underlying assumptions prove to be incorrect, the Company’s actual results may vary materially from those indicated in these statements. The Company does not undertake any obligation to publicly update or review any forward-looking statement, whether as a result of new information, future developments or otherwise. A number of important factors could cause actual results to differ materially from those indicated by the forward-looking statements. These factors include, but are not limited to, the following, any one or more of which could materially affect the outcome of future events:

These factors should not be construed as exhaustive. Additional information on these and other risk factors can be found in Item 1A. “Risk Factors” and Item 7. “Special Note Regarding Forward-Looking Statements” in the Company’s Annual Report on Form 10-K for the year ended December 31, 2014, filed with the Securities and Exchange Commission.

For further information contact:

Investar Holding Corporation

Chris Hufft

Chief Financial Officer

(225) 227-2215

Chris.Hufft@investarbank.com

INVESTAR HOLDING CORPORATION

CONSOLIDATED BALANCE SHEETS

(Amounts in thousands, except share data)