Old National Bank is a regional bank with over 150 retail branches operated by Old National Bancorp and based in Evansville, Indiana. With assets at $14.9 billion and 160 banking centers, Old National Bancorp is the largest financial services bank holding company headquartered in Indiana and one of the top 100 banking companies in the U.S. Its primary banking footprint is in Indiana, Kentucky, Michigan, and Wisconsin.

The bank was founded in 1834 as the city's first bank. It has operated under several names, including Evansville National Bank and Old State National Bank. In 1922, it was officially named Old National Bank. At the time the stock market crashed in 1929, there were 11 banks operating in Evansville; by 1935, seven of those banks had been forced to close their doors. Old National was one of the four that continued to operate. In anticipation of the impending reform of banking regulations at the state and federal levels in the late 1980s and early 1990s, the bank holding company called Old National Bancorp was formed in 1983 as a multi-bank holding company and now operates in Indiana, Michigan, Wisconsin, Kentucky and Illinois

In November 1995, Old National acquired the Greencastle-based First United Savings Bank for $18 million in stock. In the following year, Old National acquired the Bloomington-based Workingmens Capital Holdings with its Workingmens Federal Savings Bank subsidiary for an undisclosed amount in stock.

Old National participated in the Treasury Department's Troubled Asset Relief Program (TARP) with the Treasury Department buying $100 million in preferred, non-voting stock. However, by March 2009 Old National had repurchased all of its outstanding stock and had fully exited the TARP program.

In 2009, Charter One's Indiana bank branches became Old National Bank after Old National Bank bought Charter One's Indiana operations. In January 2011, Old National acquired Bloomington-based Monroe Bancorp with its Monroe Bank subsidiary for $90 million in stock. Later that year, Integra Bank was closed by the Federal Deposit Insurance Corporation and all deposit accounts, excluding certain brokered deposits, were transferred to Old National. In 2012, Old National acquired 24 retail bank branches of Bank of America in northern Indiana and southwest Michigan. In 2014, Old National acquired four banks: Tower Bank in Fort Wayne, Indiana, United Bank in Ann Arbor, Michigan, Lafayette Savings Bank in Lafayette, Indiana, and Founders Bank & Trust in Grand Rapids, Michigan.

In January 2016, Anchor BanCorp Wisconsin, the parent company of AnchorBank, the third-largest bank based in Wisconsin, announced that Old National intends to buy Anchor for approximately $461 million. The transaction closed in May of the same year.

In August 2017, Old National agreed to buy Anchor Bank of Minnesota for $303 million. The acquisition will add 17 locations in the Twin Cities and 1 in Mankato plus $1.7 billion in deposits and $2.1 billion in assets.

The company offers cash management services, lease financing, debit cards, online banking, and other electronically accessed banking services. Old National Bancorp, through other subsidiaries, also provides various services, including investment advisory and wealth management, investment and brokerage, investment consulting, and insurance agency services.

In 1995, ONB was ranked number one in earnings momentum by banking journal Financial World. The bank was rated the 28th top performing bank in the nation for 2008 by Bank Director magazine.