And, despite an Earls try, they were well in the contest at the break as captain Sergio Parisse's return to the starting XV prompted an immediate spike in their power and nous up front.
Ireland, meanwhile, had come into the game with a pair of five-point hauls against Canada and Romania but this performance was far from a perfect ten.
But it mattered little in the end for Ireland, who won 16-9 and now turn their attentions to France next weekend, when victory will see them top the pool.
Parisse, who missed each of Italy's opening two games with a calf problem, showed a bit of ring rust with an early knock-on, while Gonzalo Garcia was forced to hobble off after just three minutes, but the Azzurri didn't appear deterred.
Indeed, it took Ireland a while to find their feet but when they did, they opened the scoring, Lions fly-half Jonathan Sexton finding his way into the Italian 22 with a clean break before tapping a simple penalty between the uprights.
And when Jamie Heaslip was caught off his feet after 14 minutes, Tommaso Allan - from the Irish 22 and just to the left of the posts - restored parity.
The Irish class showed, however, on 20 minutes when, following a cute Conor Murray kick and a stolen lineout, smart work from Sexton and Robbie Henshaw sent Earls over to become Ireland's all-time leading World Cup try-scorer.
Sexton converted but when Giovanbattista Venditti powered towards Ireland's 22 and the men in green failed to roll away, Allan slotted his second penalty.
He turned down a third pop at the posts on 28 minutes, however, and opted for touch instead, only for another stolen lineout to turn the tide.
Sexton then struck the post with a long-range penalty, before a mammoth defensive shift from the Italian pack - expertly led by Parisse - took them into the break just four points behind.
Iain Henderson charged down an Allan clearance shortly after the break to pique the interest of the Irish support but Parisse calmed things down with a composed touch-finder.
The Italy skipper continued his all-action display by moving into the centres and recycling for Josh Furno to bear down on the line, but Peter O'Mahony came across and put him into touch.
Allan's third penalty reduced the gap to one, after a destructive rolling maul caused all manner of problems for the men in green, while Sexton responded in kind five minutes later.
Sexton's third penalty, after Allan failed to roll away, went some way to easing the nerves of the increasingly-anxious Irish support. Parisse's exit, prompting a standing ovation from Ireland and Italy fans alike, had a similar effect.
Carlo Canna - on for Allan - missed a long-range penalty but Ireland were soon down to 14, O'Mahony's game over after 72 minutes when he was shown a yellow card for charging into a ruck shoulder-first.
But Ireland showed their experience in the latter stages and, despite seeing Sexton miss a late penalty, snuffed out any final hopes of an Italian upset.