First-half tries by wing Alex Cuthbert and Scott Williams underpinned a healthy 17-3 interval advantage, but Italy - inspired by their brilliant captain Sergio Parisse - refused to go quietly.
Full-back Leigh Halfpenny kicked both Welsh conversions and three penalties, passing 350 Test points in the process, yet Italy arguably deserved more than centre Michele Campagnaro's second-half try double, plus a Tommaso Allan conversion and penalty.
Wales' triumph will not set alarm bells ringing in the Ireland camp ahead of Saturday's eagerly-awaited Dublin clash.
It was a scrappy, disjointed effort by the reigning Six Nations champions after they failed to increase the tempo at any point against battling opponents.
Campagnaro proved the game's dominant attacking force, and if Italy had shown a little more composure at key times then they could have left Cardiff with a famous victory.
It was Wales' seventh successive win against the Azzurri, but that statistic should not be allowed to cover up a performance that never moved out of third gear and meant they failed abysmally to make the opening weekend statement they would have wanted.
Wales centre Jamie Roberts blamed "silly mistakes" for their disappointing curtain-raiser.
"We certainly made it hard for ourselves," Roberts said. "We need a massive focus next week against Ireland on retaining the ball and no silly mistakes. We just have to look at ourselves in training this week and cut out the errors."
Ospreys lock Alun-Wyn Jones replaced Warburton as Wales skipper, with Warburton beginning his comeback after a shoulder injury on the bench, while Rhys Priestland reclaimed fly-half duties from Dan Biggar and Luke Charteris started instead of suspended second-row forward Ian Evans.
Italy saw lock Marco Bortolami win his 100th cap, but an inexperienced, injury-hit back division featured four players with just seven Test appearances between them. But despite that callow starting line-up, they defiantly held their own against a Welsh side that failed to find any real rhythym
Coach Warren Gatland, however, put a more positive spin on the result. "They made it tough for us," he said. "Italy were dogged."
Gatland said his players felt the Italians were going down with injuries too much at the breakdown."It was a bit stop-start but that is what we have got to deal with," he added.
Wales: Halfpenny, Cuthbert, S Williams, Roberts, North, Priestland, M Phillips (Webb 68), James, Hibbard (Owens 68), A Jones (R Jones 65), Charteris (Coombs 58), A Jones, Lydiate (Warburton 65), Tipuric, Faletau.
Italy: McLean, Esposito, Campagnaro, Sgarbi, Sarto (Iannone 74), Allan, Gori (Botes 66), Rizzo (De Marchi 56), Ghiraldini (Giazzon 58), Castrogiovanni (Cittadini 69), Geldenhuys, Bortolami, (Furno 69), Zanni, M. Bergamasco (Minto 58), Parisse.
Referee: J Lacey (Ireland)