The Addicks achieved the feat with a 1-0 victory away at Carlisle United earlier today.
Speaking after the match, Powell revealed that he hopes the elevation would help the club go on to bigger and better things in the future.
"It's a fantastic day for my football club and I'm really proud of my players and my staff, and all my supporters because we've had it quite tough over the past few years," he told Sky Sports News.
"This is just a small step towards us trying to make the club better again. It's a great day for us and I want everyone to enjoy it."
Powell took charge at the Valley in January 2011.