The 25-year-old midfielder drilled in his 10th goal of season in the 77th minute to pile more misery on the struggling Chairboys, after Jonjo Shelvey's classy opener had been cancelled out by Jon-Paul Pittman.
Wycombe started brightly and Stuart Beavon danced past two defenders but his shot crept just wide when one-on-one with keeper Rob Elliot, before Pittman drilled the ball into the side-netting.
However, Shelvey put Charlton ahead against the run of play in the 11th minute when he exquisitely swept Lloyd Sam's cut-back inside the far post from 15 yards.
Wycombe keeper Scott Shearer denied David Mooney, Dean Burton and Bailey as the Addicks seized control before Pittman converted Stuart Green's low cross to equalise for Wanderers in the 64th minute.
But Bailey won it for Charlton 13 minutes from the time when he fired in a loose ball from eight yards after his initial shot had been blocked.