A thrilling semifinal second leg finished 2-2 at Anfield but the advantage carved out in Manchester a fortnight ago booked Liverpool a date at Wembley next month where they will face Cardiff City.
Against the run of play, City had drawn level on aggregate with Nigel de Jong's 31st-minute cracker but nine minutes later Liverpool had their noses in front again when captain Steven Gerrard converted a penalty as he had done in the first leg.
City keeper Joe Hart had kept his side in the game with a succession of excellent saves before Edin Dzeko put the Premier League leaders 2-1 ahead on the night with a 67th minute tap-in.
Seven-time winners Liverpool were not done yet, though, and Bellamy secured their place in the final with a confident finish 16 minutes from time that Hart could do nothing about.
Cardiff had booked their place by beating fellow Championship (second division) Crystal Palace 3-1 on penalties on Tuesday after a 1-1 aggregate result.
