Rooney, 33, scored from well inside his own half with an amazing strike, seeing DC to a 1-0 victory on Thursday morning.
The former England captain, who scored similar goals for both Manchester United and Everton, said it was the type of effort he rehearsed during training - often to the bewilderment of coaches and team-mates.
"I thought it was nice and it was special to score the goal. It's something that I've practised so many times," Rooney said, via DC United's official website.
"Different managers and team-mates are like, 'Why are you practising this? You won't score from this position'. But for nights like tonight, that's why I do practice it.
"It was a good strike and an important goal for us."
Friday marks exactly a year since Rooney signed with DC and he has scored 21 goals in 38 MLS games since joining, an unquestionable success story after his relatively anticlimactic final year in English football.
Rooney, whose goal saw DC end a five-game winless league run, said he had loved his time in the United States so far.
"It's been fantastic," he said. "I've enjoyed my time here over the course of the year and there is still a lot more to come.
"We know we can play better. First half we played well, second half we know we can do better, but the win was the important thing because we haven't won in a few games in the league.
"Winning was the main thing."
Despite their poor run of late, DC remain third in the Eastern Conference table, all but secure in their place in the MLS Cup Playoffs.
Level on points with second-placed Montreal Impact with a game in hand, Rooney will be hoping his moment of magic can inspire his side even further up the table as the league season draws to a conclusion.
Next up, they host a Toronto FC side looking to keep their heads above the Playoff water in seventh.