First half goals by Carlton Cole and Jason Euell put Alan Curbishley's men in the driving seat before substitute Andy Cole set up a tense finish 15 minutes from time and US shot stopper Friedel turned home Paul Gallagher's shot for what looked like a priceless point, only for Jensen to volley home with the aid of a Markus Babbel deflection for an injury time winner.
The Addicks got off to a flying start and took a ninth-minute lead through Carlton Cole who received Paolo Di Canio's cross with his back to goal and two defenders in tow before shifting on to his left-leg and firing high at Friedel's near post.
Blackburn then began to find their feet and Australian winger Brett Emerton stung the hands of Dean Kiely with a rising right-foot drive from the right of the penalty area nine minutes later.
Emerton then put Jonathan Stead through and although Radostin Kishishev managed to hold him up, the former Huddersfield man cut inside and let fly with a right-foot shot that had Kiely beaten but not the post.
Charlton punished Rovers again on 38 minutes for not making the most of their chances when Graham Stuart chipped a ball into the box from the left which Di Canio headed into the path of Euell who made no mistake with the finish from six yards out.
Euell then squandered two more chances to increase the lead and Stead failed to make it three in three when Jonathan Douglas' through ball presented him with a chance but his lob over Kiely also cleared the crossbar.
Rovers boss Graeme Souness replaced the out-of-sorts Stead with Andy Cole for the start of the second half. Cole was quickly into the action, forcing Kiely to save at his near post with a fizzing drive from the right-hand side of the box.
Souness threw more caution to the wind on the hour mark when he introduced Cole's former Manchester United team-mate Dwight Yorke for defender Andy Todd as his side tried to claw their way back.
Mercurial Italian Di Canio very nearly scored a contender for goal of the season with a long range effort before Rovers pulled a goal back through Andy Cole.
The former England marksman anticipated Kishishev's back-pass to Kiely and got there a fraction ahead to round the Irishman and slot home despite the heroic recovery attempts of Chris Perry to rescue the goal.
Andy Cole then broke down the right soon after to flash the ball across goal that none of his team-mates anticipated, which prompted Curbishley to withdraw Carlton Cole for the calming influence of Jensen to control the midfield.
The Dane was presented with a golden chance to kill the game off with eighth minutes to go when Hermann Hreidarsson played him into acres of space but the ex-Bolton man's shot was easily saved by the onrushing Friedel.
With Charlton looking like holding out, Friedel pushed up for a corner and stunned the Charlton fans when he turned home Gallagher's shot in the 90th minute. But it was Jensen who had the final say when he looped home a deflected volley that the American could only help palm into his own net as Charlton moved up to fifth, while Rovers are still looking nervously over their shoulders at the relegation places.