Charlton, who already looked like relegation fodder although only at the halfway point of the season, were booed and heckled off the field with their supporters singing 'you're not fit to wear the shirt'.
Wycombe, who beat another Premiership side Fulham in the previous round, controlled the game from start to finish and proved what the underdogs can achieve when they are organised and motivated.
Charlton's beleaguered head coach Les Reed was looking for a morale boosting victory against his lowly opponents to instil some confidence into his shell-shattered team and made seven changes from the side that was thrashed by Liverpool on Saturday.
But Reed could only look bewildered from the touchline as the Londoners gave another X-rated horror show as their season disintegrates.
If it hadn't been for Charlton goalkeeper Scott Carson their embarrassment would have been even greater.
The on loan keeper made two outstanding saves to deny Jermaine Easter and Stefan Oakes before Wycombe took a deserved lead on 35 minutes when Tommy Mooney's through ball was controlled by Easter before firing home his 15th goal of the season.
It took Charlton 40 minutes to even get a shot on target when Bryan Hughes' free-kick was palmed away by Wycombe goalkeeper Jamie Young and then cleared to safety.
The Charlton boss did not make any substitutions until midway through the second half but they failed to improve the situation as his side slumped to defeat.
Wycombe boss Paul Lambert said before the game that it was a miracle that his side had even reached the quarter-final stage of the competition but now he must be on cloud nine with his side deservedly in the last four.
They were never in any danger of losing, apart from a belated late flurry from Charlton which the Wycombe defence dealt with capably.
After the game some Charlton supporters were shouting for recently sacked West Ham boss Alan Pardew - a former Charlton player - to take over the reins as they see their club in freefall.