Premier League's bottom club Rovers, who beat Newcastle to reach the Carling Cup quarter-finals in midweek, took the lead on the stroke of half-time through Junior Hoilett at Carrow Road.
Although Wales striker Steve Morison levelled with a well-taken strike on 53 minutes, two quick goals from Ayegbeni Yakubu and captain Christopher Samba looked to have secured a much-needed first away win for under-pressure Steve Kean.
However, the Canaries grabbed a lifeline with eight minutes left through Bradley Johnson's deflected effort.
Substitute Holt, whose scored in last week's battling 1-1 draw at Anfield, earned the never-say-die Canaries a point in stoppage time from the spot after Steven Nzonzi was harshly adjudged to have handled at the far post.
Rovers, clearly boosted by their midweek cup win, created the first opening as Mauro Formica fired a dipping 20-yard drive over.
The visitors continued their early pressure. Norwich keeper John Ruddy, who made a fine late save to earn a point at Liverpool, dropped a corner which Yakubu flicked goalwards and hit Kyle Naughton who was on the post.
The Canaries eventually opened up Rovers down the left through Marc Tierney and Anthony Pilkington, with Morison knocking the ball over from close range under pressure from Gael Givet.
Rovers should have been in front on 12 minutes, but Yakubu blazed an angled drive over after a pass from Ruben Rochina split the Norwich defence.
Slowly Norwich settled and Pilkington's fierce volley from Elliott Bennett's right-wing cross was knocked behind before David Fox was denied by a fine save at full stretch from Paul Robinson.
The home side broke through again through Morison and Pilkington down the left to cut the ball back across the face of goal. However, the on-rushing Bennett could only smash his shot into the sidenetting.
With five minutes to half-time, Blackburn won a free-kick in a dangerous position when Hoilett cut inside for the left and was tripped by Fox.
Pedersen whipped the ball towards the far post, which looped over Ruddy, but the Norwich keeper managed to recover and claim the catch before it squirmed over the line.
In stoppage time, Rovers snatched the lead when Canada-born youngster Hoilett cut in from the left again, before whipping an 18-yard effort over Ruddy into the far corner.
There was more urgency about Norwich at the start of the second half, and Morison levelled on 53 minutes with a fine finish.
Wes Hoolahan knocked the ball back into the Rovers box and an attempted clearance dropped to the Wales striker on the edge of the penalty arc. The former Millwall frontman calmly controlled the bouncing ball with his left foot before then dispatching it back with his right over Robinson.
As Carrow Road suddenly found its voice, Johnson should have done better when he met a looping cross from Pilkington into the six-yard box but his header lacked power.
Rovers, though, refused to roll over and were back in front after 62 minutes.
Yakubu got ahead of the Norwich defence on to a pass from Formica to drill the ball past Ruddy at the near post.
Before Norwich could regain their composure they were 3-1 down.
Pedersen's free-kick from the left was allowed to fly right across the six-yard box, where Samba headed in at the far post.
Lambert made some attacking changes as he sent on both Holt and Simeon Jackson.
The Canada forward broke down the left and centred for Morison, who in turn fed Holt on the overlap, but the striker's cross through the six-yard box was hacked clear by Givet.
Norwich, though, had a lifeline with eight minutes left when Johnson's deflected 20-yard shot looped up off Jason Lowe and over a stranded Robinson.
Just when Blackburn, who let in two stoppage time goals as their Carling Cup tie went into extra time, looked to have held out for a much-needed first away win, Nzonzi inadvertently handled a high ball and the referee gave a penalty.
Holt stepped up to ram the ball into the bottom left corner and earn Lambert's battling side a share of the spoils.