|Saracens (5) 24|
|Tries: Strettle, Ellery Pens: Spencer 3 Cons: Spencer Drop goals: Mordt|
|Northampton (13) 20|
|Tries: Olver, Dowson Pens: Olver 3 Cons: Olver, Myler|
Saracens reached their maiden LV= Cup final and in turn denied Northampton a home showpiece at Franklin's Gardens.
The disappointment of four losses in their last four attempts, including two against the Saints in 2010 and 2014, were brushed aside in victory.
David Strettle and Mike Ellery tries, Nils Mordt's drop goal and 11 points from Ben Spencer secured the win.
Sam Olver's 13-point first-half haul was not enough for Saints, who also saw Phil Dowson cross in the second half.
Saracens will face either Leicester or defending champions Exeter in the final on Sunday, 22 March.
These two sides have been frequent foes at the business end of competitions, notably in last season's Premiership final, and selected strong squads in the bid to secure silverware.
|Saracens LV= Cup semi-final disappointments|
|2008: Ospreys 30-3 Saracens|
|2010: Northampton Saints 31-20 Saracens|
|2013: Sale Sharks 21-15 Saracens|
|2014: Northampton Saints 26-7 Saracens|
Blustery conditions made for a attritional game, punctuated by the odd moment of skill, with Saracens character proving crucial in the second period.
After Olver twice bisected the posts with penalties, Saracens were first on the board for tries, Strettle hitting a line from deep to score on the first real foray into the opposition 22.
Olver responded for Saints, scything through with Saracens dozing at the ruck, and converted his own score to establish a 13-5 lead at the break.
Whatever was said in the Sarries sheds had an immediate effect inside the first few minutes of the second half as Ellery gathered the ball off the line out, straightened up and crashed through for a try.
Spencer rattled off a hat-trick of penalties to give Sarries a cushion but last season's runners-up fought back with a converted try from Dowson that reduced to deficit to one point.
Mordt looked to have sealed it with a late drop goal and huge defence was needed to keep Northampton out as they pressed desperately with seconds to play.
Saracens: Ransom; Ellery, Bosch, Streather, Strettle; Mordt, Spencer; Gill, Saunders, Figallo, Itoje, Smith, De Jager, Hankin, Joubert.
Replacements: Spurling for Gill (53), Barrington for Saunders (53), Alo for Figallo (73), Brown for Hankin (67).
Not Used: Kruis, Whiteley, Palamo, Fercu.
Northampton: Tuala; Elliott, Stephenson, Waldouck, Collins; Olver, Fotuali'i; Corbisiero, Haywood, Ma'afu, Manoa, Ryder, Fisher, Dowson, S. Dickinson.
Replacements: Wilson for Tuala (73), Myler for Oliver (61), L. Dickson for Fotuali'i (61), E. Waller for Corbisiero (62), Nutley for Haywood (73), Clark for Ma'afu (56), Williams for Ryder (73), Denman for Fisher (56).
Referee: Dean Richards.