Arsenal began life after Alexis Sanchez with a comeback victory over London rivals Chelsea to reach their first League Cup final in seven years.
Following a goalless first leg at Stamford Bridge, this instalment of the semi-final was more akin to the lively Premier League meeting here just 21 days ago and it was Granit Xhaka's second-half strike which set up a Wembley meeting with Manchester City on February 25.
Eden Hazard put the Blues into an early lead only for Arsenal to level through an Antonio Rudiger own goal before Xhaka settled the tie on the hour mark to seal a 2-1 win.
The Gunners were without Henrikh Mkhitaryan, their new signing watching from the stands as he is cup-tied having played in the competition for Manchester United before completing his swap deal with Sanchez on Monday night.
Arsene Wenger's side won the FA Cup last season by beating Manchester City in the semi-finals and Premier League champions Chelsea in the final and they will have to do it the hard way to lift this trophy for the first time during the Frenchman's 21-year reign.
Arsenal have not lost to Chelsea in their last six meetings and recovered well from a slow start to extend that run and book a date at Wembley next month.
Pedro tucked away an early chance for Antonio Conte's side only to be correctly flagged for offside - but the Spaniard was soon involved again, picking the ball up in plenty of space to pick a pass through for Hazard to open the scoring.
Willy Caballero showed great awareness to keep Arsenal out from their first meaningful attack, first blocking at the feet of Jack Wilshere before diving to push the ball clear with Alexandre Lacazette lurking.
Arsenal were soon on level terms, Mesut Ozil whipping in a free-kick which was met by an unmarked Nacho Monreal, whose header ricocheted off both Marcos Alonso and Rudiger before beating Caballero.
Willian dragged a shot well wide as Chelsea looked to re-establish their early lead before both sides settled into the contest.
Ross Barkley was introduced for his Blues debut as Willian hobbled off and, as Arsenal grew in confidence throughout the half, Ozil was unlucky to see a strike deflected behind on the stroke of half-time.
Wenger altered his formation at the interval, dropping Mohamed Elneny back into a three-man defence in an attempt to quieten Hazard.
The Belgium international appeared to have broken through despite those changes, only for Xhaka to launch a superb last-ditch challenge to prevent Hazard getting a shot away.
Having been instrumental at one end, Xhaka would have an impact at the other and he benefited from another fortuitous deflection off Rudiger.
Lacazette did well to keep the ball away from Andreas Christensen and, as he looked for support, his pass hit Rudiger and flashed across goal where Xhaka steered it home to put the hosts in front.
Alex Iwobi saw a great chance well saved by Caballero as Arsenal looked to put the tie beyond doubt but, after another defensive tactical tweak from Wenger, they saw at the game with relative ease.