On Michael Carrick's debut as manager, United defeated Manchester City 2-0 thanks to goals from Bryan Mbeumo and Patrick Dorgu.
Rooney said on Match of the Day: "Obviously I’m absolutely delighted. I think the team spirit, the work rate, the energy, everything about that team was fantastic today.
"I’m absolutely buzzing for the players, for the fans - the fans have been starved of that over the last few years. I know it’s only one performance but I think everyone could see how exciting that team can be.
"You hear everyone, especially us as ex-players, talk about the United DNA and that has just shown what it is. Work rate off the ball, wingers getting back filling in and helping out the full-backs.
"And the goals; crosses in the box and desire to get on the end of it. The first goal, counter-attack, sitting in and breaking fast - that is the United DNA and that was what we've been missing. And hopefully this continues.
"The work rate, the shape, the organisation of Manchester United today, the desire to get back and double up and help your teammates out and tackle and run without the ball, as quickly backwards and you do forwards. I think that was really evident today."