The Ireland captain scored the opening try before Keith Earls touched down twice in the second half as the Irish topped Pool C and booked a quarter-final match-up against Wales next weekend.
O’Driscoll pinpointed Ireland’s dominance after the break as the decisive factor in a bruising encounter in Dunedin.
â€œObviously weâ€™re delighted with the win,â€ said Oâ€™Driscoll. â€œWe were able to deliver in the second half.â€
â€œWe knew we were going to have to be patient. You have to be against any test team these days.”
He added: â€œYou have to grind them down, you have to work teams through phases so we managed to do that we were good and patient and I think we got our scores and took them clinically when we needed to.â€
The first half was a cagey affair, with fly-half Ronan Oâ€™Gara and Italyâ€™s Mirco Bergamasco trading penalty kicks as the Irish ended the opening 40 minutes with a narrow 9-6 lead.
Oâ€™Driscoll then made the crucial breakthrough after the break when he collected a pass from Tommy Bowe and burst past the wall of blue to touch down in the 47th minute.
Ireland extended their lead with another try five minutes later when Earls charged into the corner after a tremendous work from Gordon Dâ€™Arcy and Stephen Ferris in the build-up.
Rob Kearney and Bowe were denied late tries by the video referee before Earls sealed Irelandâ€™s place in the quarter-finals with a 79th-minute try.
Oâ€™Driscoll admits he is now eagerly anticipating the clash against Wales next weekend – and he expects a close game between the two northern hemisphere sides.
â€œItâ€™s going to be another great challenge for us,â€ he said. â€œItâ€™s been very close in recent years and I would envisage it being another close one.
â€œIt will be the team that turns up on the day that goes into the semi finals.â€
Ireland: Kearney, Bowe, O’Driscoll, D’Arcy, Earls, O’Gara, Murray; Healy, Best, Ross, O’Callaghan, O’Connell, Ferris, O’Brien, Heaslip.
Replacements: Cronin for Best (53), Ryan for O’Connell (58), Sexton for O’Gara (67), , Court for Healy (72), Leamy for Ferris (72), Reddan for Murray (73), Trimble.
Italy: Masi, Benvenuti, Canale, Garcia, Mirco Bergamasco, Orquera, Semenzato; Perugini, Ghiraldini, Castrogiovanni, Geldenhuys, Van Zyl, Zanni, Mauro Bergamasco, Parisse.
Replacements: Lo Cicero for Castrogiovanni (34), Bocchino for Orquera (40), Derbyshire for Mauro Bergamasco (49), Gori for Semenzato (56), Bortolami for van Zyl (61), Ongaro for Ghiraldini (67).
MORE: The latest football news
MORE: The latest tennis news