Rooney, who played for DC United between 2018-19, stepped down as manager of Derby County last month, ending a turbulent 17-month spell during which the English club were marred by financial trouble and relegated to the third tier.
Rooney had been in talks with the U.S. club for weeks, according to the reports on Sunday, and will replace interim coach Chad Ashton, who took charge after the departure of Hernan Losada in April.
ESPN reported that Rooney would join up with the club once the final details were worked out and he had received a work visa.
DC United are second from bottom in the Eastern Conference with 17 points from 17 matches. They were thrashed 7-0 by Philadelphia Union in their last game.
Rooney scored 253 goals for Manchester United and won five Premier League titles and the Champions League with the club. For DC United, he was their top scorer and MVP in 2018 and made the MLS All-Star Team in 2019.
He joined Derby in a player-coach capacity in 2020 before being named manager the following year.
