Pompey's route to a second FA Cup final in the space of three seasons saw them thrash south coast rivals Southampton on their own patch.
After a goalless first half, Quincy Owusu-Abeyie opened the scoring in the fifth round contest at St Mary's.
Rickie Lambert levelled for the hosts, but strikes from Aruna Dindane, Nadir Belhadj and Jamie O'Hara ensured a comfortable victory for Avram Grant's side.