Exhibit 99.1

ACI Worldwide, Inc. Reports Financial

Results for the Quarter Ended June 30, 2015

HIGHLIGHTS

NAPLES, FLA — July 30, 2015 — ACI Worldwide (NASDAQ: ACIW), a leading global provider of electronic payment and banking solutions, today announced financial results for the period ended June 30, 2015. Management will host a conference call at 8:30 am ET to discuss these results. Interested persons may access a real-time audio broadcast of the teleconference at http://investor.aciworldwide.com/ or use the following numbers for dial-in participation: US/Canada: (866) 914-7436, international: +1 (817) 385-9117. Please provide your name, the conference name ACI Worldwide, Inc. and conference code 87676766. There will be a replay available for two weeks on (855) 859-2056 for US/Canada callers and +1 (404) 537- 3406 for international participants.

“ACI had a busy and successful second quarter. We delivered net new bookings growth of 18% and signed several important renewals, including a five-year extension with the IRS,” commented Phil Heasley, President and CEO, ACI Worldwide. “We also signed another Universal Payments contract, this time with a large existing customer that has decided to upgrade their Faster Payments infrastructure. Looking to the second half of the year, our pipeline remains very strong and we are tracking well to achieve our targets this year and beyond.”

FINANCIAL SUMMARY

Financial Results for Q2

Overall sales bookings, including term extensions, increased 24% compared to the prior year quarter. New sales bookings, net of term extensions (SNET), increased 18% compared to the prior year quarter.

We ended Q2 with a 12-month backlog of $883 million and a 60-month backlog of $4.1 billion. After adjusting for foreign currency fluctuations, our 12-month backlog declined $11 million and our 60-month backlog declined $10 million from Q1 2015. An internal decision to exit one bill payment vertical as a result of regulatory changes negatively impacted our 60-month backlog by approximately $30 million. Excluding this, 60-month backlog grew $20 million.

Non-GAAP revenue in Q2 was $266 million, an increase of $11 million, or 4%, above the prior year quarter.

Adjusted EBITDA of $58 million was up 3% from last year’s $56 million. Net EBITDA margin in Q2 2015 was 25%, or flat with Q2 2014, after adjusting for $38 million and $34 million of pass through interchange fees in Q2 2015 and Q2 2014, respectively.

Q2 non-GAAP net income was $30 million, or $0.26 per diluted share, versus non-GAAP net income of $14 million, or $0.12 per diluted share in Q2 2014.

ACI ended the second quarter with $50 million in cash on hand. Following $84 million in net debt payments during the first half of 2015, ACI ended the quarter with a debt balance of $808 million. Operating free cash flow (OFCF) for the quarter declined from Q2 2014 primarily driven by the timing of Q2 2015 sales receipts now expected in early Q3.

During the quarter, ACI received cash proceeds of $35 million and realized a $24 million gain from the sale of our holding in Yodlee, Inc stock.

Reiterating Guidance

We expect to generate non-GAAP revenue in the range of $1.04 to $1.07 billion for the full year 2015. This range continues to represent 3-6% organic growth after adjusting for foreign currency fluctuations. We expect adjusted EBITDA to be in the range of $280 to $290 million. We expect to generate between $235 and $245 million in non-GAAP revenue in the third quarter. Lastly, we expect full year 2015 net new sales bookings to increase in the upper single digit range.

About ACI Worldwide

ACI Worldwide, the Universal Payments company, powers electronic payments and banking for more than 5,600 financial institutions, retailers, billers and processors around the world. ACI software processes $13 trillion each day in payments and securities transactions for more than 300 of the leading global retailers, and 18 of the top 20 banks worldwide. Through our comprehensive suite of software products and hosted services, we deliver a broad range of solutions for payment processing; card and merchant management; online banking; mobile, branch and voice banking; fraud detection; trade finance; and electronic bill presentment and payment. To learn more about ACI, please visit www.aciworldwide.com. You can also find us on Twitter @ACI_Worldwide.

^© Copyright ACI Worldwide, Inc. 2015.

For more information contact:

John Kraft, Vice President, Investor Relations & Strategic Analysis

ACI Worldwide

239-403-4627

john.kraft@aciworldwide.com

To supplement our financial results presented on a GAAP basis, we use the non-GAAP measures indicated in the tables, which exclude certain business combination accounting entries related to the acquisition of Online Resources Corporation and significant transaction-related expenses, as well as other significant non-cash expenses such as depreciation, amortization and share-based compensation, that we believe are helpful in understanding our past financial performance and our future results. The presentation of these non-GAAP financial measures should be considered in addition to our GAAP results and are not intended to be considered in isolation or as a substitute for the financial information prepared and presented in accordance with GAAP. Management generally compensates for limitations in the use of non-GAAP financial measures by relying on comparable GAAP financial measures and providing investors with a reconciliation of non-GAAP financial measures only in addition to and in conjunction with results presented in accordance with GAAP. We believe that these non-GAAP financial measures reflect an additional way to view aspects of our operations that, when viewed with our GAAP results, provide a more complete understanding of factors and trends affecting our business. Certain non-GAAP measures include:

ACI is also presenting operating free cash flow, which is defined as net cash provided by operating activities, plus payments associated with acquired opening balance sheet

liabilities, net after-tax payments associated with employee-related actions and facility closures, net after-tax payments associated with significant transaction-related expenses, and less capital expenditures. Operating free cash flow is considered a non-GAAP financial measure as defined by SEC Regulation G. We utilize this non-GAAP financial measure, and believe it is useful to investors, as an indicator of cash flow available for debt repayment and other investing activities, such as capital investments and acquisitions. We utilize operating free cash flow as a further indicator of operating performance and for planning investing activities. Operating free cash flow should be considered in addition to, rather than as a substitute for, net cash provided by operating activities. A limitation of operating free cash flow is that it does not represent the total increase or decrease in the cash balance for the period. This measure also does not exclude mandatory debt service obligations and, therefore, does not represent the residual cash flow available for discretionary expenditures. We believe that operating free cash flow is useful to investors to provide disclosures of our operating results on the same basis as that used by our management.

ACI also includes backlog estimates, which include all software license fees, maintenance fees and service fees specified in executed contracts, as well as revenues from assumed contract renewals to the extent that we believe recognition of the related revenue will occur within the corresponding backlog period. We have historically included assumed renewals in backlog estimates based upon automatic renewal provisions in the executed contract and our historic experience with customer renewal rates.

Backlog is considered a non-GAAP financial measure as defined by SEC Regulation G. Our 60-month backlog estimate represents expected revenues from existing customers using the following key assumptions:

Estimates of future financial results are inherently unreliable. Our backlog estimates require substantial judgment and are based on a number of assumptions as described above. These assumptions may turn out to be inaccurate or wrong, including, but not limited to, reasons outside of management’s control. For example, our customers may attempt to renegotiate or terminate their contracts for a number of reasons, including mergers, changes in their financial condition, or general changes in economic conditions in the customer’s industry or geographic location, or we may experience delays in the development or delivery of products or services specified in customer contracts which may cause the actual renewal rates and amounts to differ from historical experiences. Changes in foreign currency exchange rates may also impact the amount of revenue actually recognized in future periods. Accordingly, there can be no assurance that contracts included in backlog estimates will actually generate the specified revenues or that the actual revenues will be generated within the corresponding 60-month period.

Backlog should be considered in addition to, rather than as a substitute for, reported revenue and deferred revenue.

Forward-Looking Statements

This press release contains forward-looking statements based on current expectations that involve a number of risks and uncertainties. Generally, forward-looking statements do not relate strictly to historical or current facts and may include words or phrases such as “believes,” “will,” “expects,” “anticipates,” “intends,” and words and phrases of similar impact. The forward-looking statements are made pursuant to safe harbor provisions of the Private Securities Litigation Reform Act of 1995.

Forward-looking statements in this press release include, but are not limited to, statements regarding: (i) expectations regarding pipeline strength; (ii) expectations that ACI is tracking well to achieve targets this year and beyond; (iii) expectations regarding non-GAAP revenue, adjusted EBITDA, and net new sales bookings in 2015; and (iv) expectations regarding Q3 2015 non-GAAP revenue.

All of the foregoing forward-looking statements are expressly qualified by the risk factors discussed in our filings with the Securities and Exchange Commission. Such factors include, but are not limited to, increased competition, the performance of our strategic product, UP BASE24-eps, demand for our products, restrictions and other financial covenants in our credit facility, consolidations and failures in the financial services industry, customer reluctance to switch to a new vendor, the accuracy of management’s backlog estimates, the maturity of certain products, our strategy to migrate customers to our next generation products, ratable or deferred recognition of certain revenue associated with customer migrations and the maturity of certain of our products, failure to obtain renewals of customer contracts or to obtain such renewals on favorable terms, delay or cancellation of customer projects or inaccurate project completion estimates, volatility and disruption of the capital and credit markets and adverse changes in the global economy, our existing levels of debt, impairment of our goodwill or intangible assets, litigation, future acquisitions, strategic partnerships and investments, risks related to the expected benefits to be achieved in the transaction with Retail Decisions, the complexity of our products and services and the risk that they may contain hidden defects or be subjected to security breaches or viruses, compliance of our products with applicable legislation, governmental regulations and industry standards, our compliance with privacy regulations, the protection of our intellectual property in intellectual property

litigation, the cyclical nature of our revenue and earnings and the accuracy of forecasts due to the concentration of revenue-generating activity during the final weeks of each quarter, business interruptions or failure of our information technology and communication systems, our offshore software development activities, risks from operating internationally, including fluctuations in currency exchange rates, exposure to unknown tax liabilities, and volatility in our stock price. For a detailed discussion of these risk factors, parties that are relying on the forward-looking statements should review our filings with the Securities and Exchange Commission, including our most recently filed Annual Report on Form 10-K and our Quarterly Report on Form 10-Q.

ACI WORLDWIDE, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED BALANCE SHEETS

(unaudited and in thousands, except share and per share amounts)

ACI WORLDWIDE, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF INCOME

(unaudited and in thousands, except per share amounts)

ACI WORLDWIDE, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(unaudited and in thousands)

ACI WORLDWIDE, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(unaudited and in thousands)

ACI Worldwide, Inc.

Reconciliation of Selected GAAP Measures to Non-GAAP Measures (1)

(unaudited and in thousands, except per share data)