It will be Fitzgerald's first start at full-back in a Six Nations match. He previously donned the number 15 jersey for the November win over Samoa.
The final change to the back-line sees Tomas O'Leary come in at scrum half after missing all of the GUINNESS Series in November due to a thumb injury.
In the pack, Rory Best returns to the side at hooker with Mike Ross earning his first Six Nations start at tighthead prop.
Paul O'Connell, who was also sidelined for the November internationals, returns to the team to earn his 71st cap in the second row.
The back row contains a new combination at international level, with Denis Leamy selected alongside his Munster colleague David Wallace and Leinster's Sean O'Brien, who is another first-time starter in the Championship.
Commenting on the team selection, Ireland head coach Declan Kidney explained his reasoning behind playing Fitzgerald at full-back and Earls, who is also comfortable in the position, on the wing.
"If it's a head-to-head between Keith and Luke, Keith is quite comfortable on the wing. Luke doesn't mind playing on the wing, (but) he prefers to play full-back and when it comes to something like that you pick a guy who will play better in a position he prefers," he said.
"The big person to lose out is Gavin Duffy. Gavin was very unfortunate to lose out in this order, but I thought the combination that Fergus, Luke and Keith give us in the back-three is a good one for us in the way we want to play."
Front rower Ross, who has been a regular starter for Leinster this season, will win his third Ireland cap and first since the 2009 summer tour to Canada and the USA.
Confident that he will make the step up to Championship level, Kidney said: "Obviously Mike has been playing well recently and deserves his go. Of all the Irish-qualified props that are playing, he is playing the best at the moment. He is fit, so deserves a go."
O'Connell's return to the side sees him link up once again with Donncha O'Callaghan in a vastly-experienced lock combination that has served Ireland well over the years.
"Donncha has been a stalwart of the team over the last number of years. There is huge competition for the place, both from Leo (Cullen) and Mick O'Driscoll.
"It's impossible to play them all at the one time, but Donncha and Paul have been a good combination for us. So, I see no reason not to go with them."
IRELAND Team & Replacements (v Italy, 2011 RBS 6 Nations Championship, Stadio Flaminio, Saturday, February 5, kick-off 3.30pm local time/2.30pm Irish time):
15 - Luke Fitzgerald (Blackrock College/Leinster)
16 - Sean Cronin (Buccaneers/Connacht)
17 - Tom Court (Malone/Ulster)
18 - Leo Cullen (Blackrock College/Leinster)
19 - Shane Jennings (St. Mary's College/Leinster)
20 - Eoin Reddan (Lansdowne/Leinster)
21 - Ronan O'Gara (Cork Constitution/Munster)
22 - Paddy Wallace (Ballymena/Ulster)
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