Dale Stephens' stunning strike put Charlton ahead before Jordan Rhodes headed in his 15th league goal for Rovers.
But the Addicks snatched the points through Yann Kermorgant's firm header.
"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."
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 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."
