When the former England captain was unveiled as DC United’s marquee signing this year, they were bottom of the MLS Eastern Conference with two wins in 14 matches and had been eliminated from the U.S. Open Cup.
However, 12 goals and seven assists in 19 appearances from the former Everton and Manchester United man has helped DC United climb up the standings to fifth and reach the playoffs with one game of the regular season to spare.
The team are now unbeaten since the end of August and have won their last five matches.
"Playoff spot secured. Proud of this team!" Rooney posted on Twitter on Monday along with a picture of the squad after the win over NYCFC.
"He's a great player, very easy to play with. He makes everything easier," fellow DC United forward Luciano Acosta said.
DC United's next match is a trip to Chicago Fire, with the possibility of third place in the Eastern Conference up for grabs should they win.
Such a finish would ensure home advantage in the first round of the playoffs.
The MLS is divided into two divisions, the Eastern Conference and the Western Conference, with the post-season playoffs determining the ultimate winner of the MLS Cup.