The congresswoman from New York defeated Rep. Gerry Connolly, D-Va., by a vote of 133-86.
"I am deeply humbled and grateful to my colleagues for entrusting me with the chairmanship," Maloney said. "I'm honored by this opportunity to do more for the American people and will do my best to follow the honorable example that Chairman Cummings left for us all. There's much work to be done, and I can't wait to get started."
Maloney is the longest-serving Democrat on the committee, having joined the panel in 1993. She served as acting chairwoman after former Chairman Cummings died in October.
The House Committee on Oversight and Reform is the primary investigative committee in the lower chamber. It's one of three House panels involved in the impeachment inquiry into President Donald Trump. Also involved are the House foreign affairs and intelligence committees.
Maloney is the first woman to lead the panel since its creation in 1927.