The Portuguese outfit went into their second leg in Italy with a 4-1 advantage and they never looked like succumbing to a toothless Lazio attack.
The game in truth was almost the exact opposite to two weeks previous, when the clubs shared five goals.
Porto were happy to sit back and attempt to catch the home side on the break, which they did with limited success.
The only real incident of note in the first period was the double dismissal of Lazio defender Cesar and Porto's striking sensation Helder Postiga (pictured).
Both players were already on yellow cards when they clashed in what appeared to be an innocuous incident just before half time, but French official Gilles Veissiere handed both a second caution - which rules Postiga out of the final.
After the break Lazio pushed forward and again a Veissiere decision - just before the hour mark - proved a major turning point.
Simone Inzaghi was held back by Jorge Costa on the goal-line after he challenged Vitor Baia and looked to scramble the ball home.
Claudio Lopez stepped up and hammered a low shot towards goal, but Vitor Baia produced a wonderful save to his left to keep Lazio out.
The miss totally deflated the Italians and they barely managed another attack, albeit a half chance for Lopez from a Sinisa Mihajlovic cross just a few minutes after his penalty failure.
Porto could and should have sealed victory with Dmitry Alenichev and Derlei guilty of spurning good chances.
Lithuanian striker Edgaras Jankauskas could have won it in the final minute, but his effort was well blocked by Luca Marchegiani.
Porto are now in the final, but they will not face city rivals Boavista after Celtic booked their place in Seville.
Click below for match summary:
Lazio 0-0 Porto
