Bradley Wright-Phillips scored his first goal since November as a packed crowd at The Valley saw Charlton move 10 points clear at the top of League 1 on Saturday.
More than 25,500 fans took advantage of Charlton's football for a fiver promotion, and manager Chris Powell's side delivered the goods with two second-half goals.
Wright-Phillips (pictured) went close to scoring in the first half, heading over a Danny Green cross and then collecting Yann Kermorgant's pass but firing inches over.
Former Gills forward Luke Freeman went closest for Stevenage but he just failed to turn in a cross from former Charlton and Ebbsfleet midfielder Stacy Long.
Charlton took the lead on 49 minutes when a corner was only half-cleared and Michael Morrison fired home from the edge of the box to break the deadlock.
Wright-Phillips scored his 15th goal of the season - his first strike in 13 games - when he collected Dale Stephens' pass and fired in, his shot taking a deflection off Jon ashton on its way beyond keeper Chris Day in the 64th minute.
Day prevented his side from losing by an even bigger margin late on, denying Wright-Phillips and substitute Danny Haynes.
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