And Scott Parker was allowed to run 40 yards before sliding the ball past Paul Robinson two minutes into added time.
For the first time this season, Venables managed to field the same team in two consecutive matches, and there was more good news for the beleaguered manager with the return to the bench of Danny Mills and Robbie Fowler.
His side looked up to the task and got a good response from the previously critical fans as Kewell went close with a sixth minute shot after a good run.
In a surprisingly open match, Shaun Bartlett rattled the bar with a header from a corner at one end and Eirik Bakke had an effort cleared off the line by Jason Euell.
Leeds had most of the possession but Charlton looked dangerous on the break with Paul Robinson pulling off good saves to deny Lisbie and Euell.
Kewell was beginning to get stick from the crowd for a lack of effort, but there was no doubting at his commitment for the opening goal.
Smarting from what he thought was an unpunished elbow in his face, the Aussie striker shrugged off Gary Rowett, took on two more defenders and crashed a shot high into the top corner from just outside the area.
Leeds were gradually being pegged back and it was no more than Charlton deserved when Bartlett climbed high to head into the path of Lisbie, who made no mistake with his right foot drive from 12 yards.
Venables sent on Fowler and Michael Bridges and his gamble almost paid off when Bridges slammed a first time shot against the post.
But with only a minute of injury time left, Parker robbed Kewell far too easily and was allowed to run into the box and grab the winner.