The Addicks gained their second consecutive away win, and Powell said the players' positive attitude made a difference.
"I think we've been very positive away from home this season," Powell said.
"We've had some good results on the road and the team warranted their places after their performances last week. We were very positive in our mindset and I think it showed today."
Only Hull and Watford have better away records than Charlton this season, and Powell was pleased with how his side dealt with Rovers having a new manager.
He said: "We're extremely pleased and I'm very proud of the players today because we had the factor of a team having a new manager and looking to impress the new manager and we've known over the years what normally happens.
"So it was up to us to make sure we got our tactics and performance right and ultimately over the 90 minutes, we did."