Sportal.co.nz 29.Jan.2014Getty Images
The open-side flanker has not played since injuring a shoulder against Australia in November.
Although Warburton has made good progress in training, his place in the side goes to Ospreys' Justin Tipuric, while second-row Alun Wyn Jones takes over as captain.
Jones led the British and Irish Lions in Warburton's absence when the latter was ruled out of the third and final Test with Australia last year.
Wales are without a trio of forwards, with Gethin Jenkins (knee) and Ryan Jones (hamstring) missing through injury and Ian Evans banned.
Yet coach Warren Gatland is happy with the options at his disposal as Wales target a third successive Six Nations crown.
"It's a strong, experienced side, but there was a lot of discussion about the selection which is a great position to be in as a coach," said the New Zealander.
"We've almost everyone fit for selection which is pretty rare.
"Italy started last year's tournament with a win over France so they will be ready on Saturday and we need to start well and build confidence and momentum."