Bentley and Pavlyuchenko looked to be heading out of the exit door back in January but they have both taken their chance in the first team and have played a major role in helping the north London club reach the last four of the competition.
Tottenham had to do it the hard way after former striker Bobby Zamora had put Fulham into the lead.
But Spurs hit back and goals from Bentley, Pavlyuchenko and Eidur Gudjohnsen made it another memorable cup evening at White Hart Lane.
For Redknapp it will be an extra special day facing a club he managed on two separate occasions and he will be looking to win his first major trophy as Tottenham boss.
Fulham could have opened the scoring after just 10 minutes when former Tottenham midfielder Simon Davies saw his dipping shot produce a fine save by Heurelho Gomes.
The west London club saw their early dominance pay off when they broke the deadlock on 17 minutes.
Damien Duff played the ball into Zamora just inside the box and he produced a clinical finish when he slotted the ball past Gomes into the corner of the net.
Tottenham slowly clawed their way back into the game and came close to grabbing an equaliser on 28 minutes when Gareth Bale's cross picked out Gudjohnsen, who used his chest to flick the ball into the path of Luka Modric and he fired a shot inches past the post.
It could have been a different story for Fulham if they had put away two golden chances on the stroke of half-time.
Duff's corner picked out Brede Hangeland, who rose the highest in the box and saw his close-range header fall just over the bar.
And they came even closer just seconds later when Zoltan Gera's cross picked out Zamora, who was completely unmarked inside the box but he directed his header over the bar.
Redknapp took drastic action at half-time when he made a double substitution and brought on Bentley and Tom Huddlestone.
The move paid off straight away as Bentley brought the home side level on 47 minutes.
Stephen Kelly brought down Gareth Bale and received a yellow card for his late challenge.
Tottenham made full use of the set-piece when Bentley swung his free-kick into the box and his dipping shot evaded everyone in the box and the ball flew past Mark Schwarzer into the corner of the net.
The Tottenham fans could start dreaming about Wembley again and their night was to get even better when fans favourite Pavlyuchenko put them in the lead in spectacular fashion on 59 minutes.
Bentley was involved in the heart of the action once again when his deep cross into the box picked out the Russian striker, who fired an unstoppable volley past Schwarzer.
Tottenham put the game beyond Fulham when Gudjohnsen added a third on 65 minutes.
Modric's pass picked out the former Chelsea forward who flicked the ball over Schwarzer and tapped the ball home from close range to book a place at Wembley on April 11th.