The 36-year-old played for DC United in 2018 and 2019, scoring 25 goals in 52 matches, but will now return to manage his former side after resigning from his post at Derby County.
The former England man was filmed arriving at Dulles Airport on Sunday night as he closes in on a return in the dug-out.
But Rooney travelled alone, without his wife Coleen, who struggled to settle in Washington when he was a player there.
According to Sportsmail, Rooney has been asking players based in England to join him at DC in recent weeks.
Rooney is close to agreeing on a deal with the club, as he told supporters at the DC airport that he still had ‘few things to sort out.’
Meanwhile, The Washington Post reports that Rooney is expected to agree to a multi-year contract worth at least $1 million (£830,000) annually. He will act as a consultant for DC United until he is granted a work permit, which typically takes two to three weeks.
Rooney will inherit a struggling DC United team that is sitting at the second bottom of the MLS Eastern Conference, having won just five of 17 matches so far this season.
The MLS side were beaten 7-0 by Philadelphia in their latest outing on Saturday, the heaviest defeat in the history of the club.
Rooney will take over from interim coach Chad Ashton, who will return to the assistant coach role he has performed for the last 15 years.