Two tries from JP Estelles and further efforts from Tom Kessell, Nafi Tuitavake, Charlie Clare and Rory Hutchinson got the job done, with Sam Olver, who shrugged off the windy conditions to add 19 points with the boot.
Saracens had impressed during the first half, but missed kicks from fly-half Max Malins saw them go in 17-12 down at the break.
And the strong Wanderers side simply had too much strength and skill after the break as they stormed into the final, which will be against Gloucester at the Gardens on Monday, May 1.
James Wilson showed his class early on in the semi-final, slaloming his way from the Wanderers 22 into Saracens territory, and the home side soon won a penalty, which Olver missed.
But Olver soon made amends, cleverly making the most of some territory to land a drop goal.
Saracens had the chance to respond with a penalty of their own, but Malins sent it to the right of the posts.
And he soon repeated the miss with another tee kick from a similar position as Saracens spurned two chances to level the scores.
But the away side had been dominating possession and it wasn’t long before they grabbed a try as a surge into the Wanderers half ended with scrum-half Henry Taylor burrowing over.
Malins still couldn’t find his kicking boots as he fluffed the conversion and the Wanderers were able to reclaim the lead as No.9 Kessell picked up the pieces from a scrum to score.
Olver converted to make it 10-5, but Saracens were back in front when Taylor’s lovely weaving run and offload set up Dominic Morris to score.
Malins converted, but the Wanderers responded immediately as Ben Nutley set up Tuitavake for a try, which Olver added the extras to.
Malins had a chance to cut the gap with the final kick of the half, but his frustration continued as he once again missed a penalty chance.
And Olver made him pay with a penalty of his own in the first minute of the second half to take the Wanderers eight points clear.
Saracens were soon under pressure and after the Wanderers set up a lineout, Clare made the most of the forward momentum to score.
Olver missed the kick, but the advantage was now a comfortable one and it was even safer when a lovely Christian Day offload set up Estelles for a clear run to the line.
Olver converted superbly to make it 32-12 and the Wanderers opted to introduce George Pisi from the bench as he returned from the shoulder injury he suffered at Leinster in December.
But Saracens issued a rapid riposte as Alistair Crossdale scored and Malins converted well from out wide.
Olver put the Wanderers back on track with a penalty and Estelles was soon grabbing his second score of the night as good work from Pisi and Nutley set him up in the corner.
Olver again put the icing on the cake with a lovely conversion from the touchline to take the score to 42-19.
Nathan Earle grabbed a try as Saracens refused to go quietly, with Malins again converting.
But more good work from Pisi and Nutley helped to set up Hutchinson for the Wanderers’ sixth score, with Olver again converting superbly.
There was still time for Saracens to score again as Crossdale sped in for his second.
But Malins missed the conversion and it was too little, too late for Saracens as the Wanderers won with ease.
Wanderers: Wilson; Estelles (Grayson 75), Tuitavake (G Pisi 54), Hutchinson, Collins; Olver, Kessell (Mitchell 70); Ma’afu (E Waller 51), Clare (Fish 66), Denman (Ilnicki 54); Paterson (J Onojaife 66), Day; Nutley, Ludlam, Dickinson (c) (Allman 74).
Saracens Storm: Earle; Crossdale; Gallagher, Morris, Ellery; Malins, Taylor; Thompson-Stringer (Adams-Hale 51), Saunders (Lindsay 40), Alexis (Hughes 51): Lemalu (Flanagan 57), Isikewe, Nay, Spurling (Conlon 57), Earl.
Referee: John Meredith