Citizens Financial Group, Inc. is an American bank headquartered in Providence, Rhode Island, which operates in the states of Connecticut, Delaware, Indiana, Illinois, Massachusetts, Michigan, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode Island and Vermont. Citizens is a wholly owned subsidiary of the Royal Bank of Scotland Group, with headquarters based in Edinburgh, Scotland, UK.

Citizens was first established in 1828 as the High Street Bank in Providence, Rhode Island. In 1871, the Rhode Island legislature gave a second charter to establish the Citizens Savings Bank which eventually acquired its parent group to form Citizens Trust Company. The bank then expanded through Rhode Island, opening a total of 29 branches in that state. Citizens Financial Group was established as a holding company when the bank acquired The Greenville Trust Company in 1954.

In 1985, Citizens changed status from a mutual savings bank to a federal stock savings bank. Expansion into other states began with Massachusetts in 1986. In 1988, Citizens accepted a takeover bid from the Scottish based bank, the Royal Bank of Scotland (RBS), which used Citizens Bank as a stepping stone into the American market. In the following sixteen years under RBS ownership, Citizens acquired several smaller banks in the New England area to become the second largest bank in the region. In 1996, the acquisition of First NH Bank saw the Bank of Ireland gain a 23.5% stake in Citizens, which was repurchased two years later by RBS.

Expansion outside New England began in 2001, when RBS purchased the retail banking division of Mellon Financial Corporation in Pennsylvania, New Jersey and Delaware, and three years later, bought Cleveland-based Charter One Bank for $10.5 billion with branches in Illinois, Ohio, Indiana, Michigan, upstate New York, and Vermont. (The Charter One name was retained in the Midwest where a different Citizens Bank operates, though it adopted a logo similar to Citizens. Charter One branches in New York and Vermont were re-branded as Citizens Bank.) The deal made Citizens Financial the ninth largest bank in the United States with over $128 billion in assets and 1,400 branches across 13 states, making Citizens Financial Group contribute 25% to the profits of RBS. In July 2003, the bank purchased the naming rights to the new home field of the Philadelphia Phillies, calling it Citizens Bank Park. In 2004 RBS purchased the financially disastrous credit card division of Connecticut-based People's Bank. This purchase allows Citizens to issue and market its own credit cards. In addition, RBS purchased Lynk systems of Atlanta, Georgia to processes non-cash transactions (such as credit, debit, EBT, loyalty, gift, and check transactions) from merchant point-of-sale terminals, web sites, and ATMs. The company has been rebranded as RBS Lynk. In addition, Citizens is one of the first banks in America to use RFID technology on its ATM cards, via MasterCard PayPass.

In early 2005, seven Citizens Bank branches in Butler County, Pennsylvania had planned to be rebranded with the Charter One name. This rebranding resolved a 3½-year-old name dispute with Butler-based Citizens National Bank. By mid-2005, Citizens National and Citizens Financial agreed to a compromise. Citizens National Bank changed its name to NexTier Bank, while the Citizens Financial Group branches maintained the "Citizens Bank" name.

A new corporate logo, designed to show Citizens Bank's connection to the Royal Bank of Scotland Group, debuted in 2005.

In February 2007 the Charter One franchise acquired GreatBank, GreatBank Chicago, and First National Bank — all brands of GreatBanc Inc of Chicago, IL. With this acquisition came GreatBanc's 10 banking locations and 14 ATMs throughout Cook, McHenry and Will counties. This transaction expands Charter One’s presence in Chicago, Skokie and Evanston and provides entry into the towns of Olympia Fields, Chicago Heights, Frankfort, Cary and Algonquin.

On September 1, 2007, the individual banks under Citizens Financial Group, excluding Citizens Bank of Pennsylvania, were merged into RBS Citizens, N.A.