Eagles broke the deadlock with a close-range effort, after the ball had bounced around in the Charlton box following a corner.
With nobody able to clear the danger, Tangerines defender Nyron Nosworthy headed towards goal and Eagles was the man on hand to turn it home.
It was a deserved lead for Lee Clark's men, who are looking for their second Championship win on the bounce following victory over Birmingham City last weekend.
However, it did not last long, as a penalty was awarded when Igor Vetokele was bundled over in the box.
On-loan Belgian Buyens stepped up and sent Joe Lewis the wrong way, levelling things up before the interval.