Stand-in goalkeeper Lukasz Fabianski was the hero as his two saves in a penalty shoot-out helped Arsenal beat holders Wigan at Wembley to reach their first FA Cup final since 2005.
After a bright start by Arsenal, it was Wigan who went ahead through a penalty from Jordi Gomez just after the hour.
However the Gunners made it 1-1 with seven minutes left through Per Mertesacker, whose foul had given away the spot-kick.
After Alex Oxlade-Chamberlain had hit the crossbar in extra-time, it was down to penalties.
Fabianski - standing in again for regular number one Wojciech Szczesny - produced fine saves from Gary Caldwell and Jack Collison, before Santi Cazorla rolled in the winning penalty to secure a 4-2 shoot-out success.