Matty Godden's double took his tally to 21 goals this season and helped Charlton finish fourth in League One as they saw off Burton Albion 3-1.
The Addicks, unbeaten in 15 matches at The Valley, will face Wycombe in the play-off semi-finals.
Charlton fell behind in the 13th minute, Mason Bennett converting from the penalty spot after Fabio Tavares was brought down by goalkeeper Ashley Maynard-Brewer.
Godden restored parity in the 24th minute, Charlton's top scorer finishing from the right of the penalty box with Burton keeper Max Crocombe making a bad call to stray from his line to try to reach Tennai Watson's through ball.
Godden doubled his tally in the 34th minute, producing a sharp turn from Josh Edwards' pass to beat Crocombe, who managed to get a hand to his low left-footed shot but could not keep it out.
Alex Mitchell, whose poor backpass had led to the early penalty, made amends when he headed in Conor Coventry's in-swinging corner in the 51st minute to put Charlton 3-1 ahead.
It could have been four but Addicks debutant Ibrahim Fullah hit the right post from Karoy Anderson's cutback.
Match report supplied by PA Media.
