The Montpellier number 10 missed the opening two games of the tournament with a knee injury and replaces Tommaso Allan, while wing Pierre Bruno is another change from the team that lost 31-14 to England last time out.
He takes over from Tommaso Menoncello, who moves to inside centre as Luca Morisi misses out.
The back three also contains Ange Capuozzo in the number 15 jersey and wing Edoardo Padovani, while Juan Ignacio Brex keeps his place at outside centre and scrumhalf Stephen Varney partners Garbisi.
The front row is made up of hooker Giacomo Nicotera and props Danilo Fischett and Simone Ferrari, the latter in the side for Marco Riccioni.
The rest of the pack is unchanged, with locks Niccolo Cannone and Federico Ruzza in front of loose-forwards Sebastian Negri, captain Michele Lamaro and Lorenzo Cannone.
"Every game has a different story," coach Kieran Crowley said in a media release from Italian Rugby. "We will face Ireland aware of what we did against France and England with the aim of improving in some areas that will make us more competitive.
"It will be a tough game against the number one team in the world and we can't wait to face them."
Italy have four wins in 34 previous matches against Ireland, though their only success since 1999 came in a 22-15 Six Nations victory in Rome a decade ago.
Italy team:
15. Ange Capuozzo, 14. Edoardo Padovani, 13. Juan Ignacio Brex, 12. Tommaso Menoncello, 11. Pierre Bruno, 10. Paolo Garbisi, 9. Stephen Varney; 1. Danilo Fischetti 2. Giacomo Nicotera, 3. Simone Ferrari, 4. Niccolo Cannone, 5. Federico Ruzza, 6. Sebastian Negri, 7. Michele Lamaro, 8. Lorenzo Cannone
Replacements:
16. Luca Bigi, 17. Federico Zani, 18. Marco Riccioni, 19. Edoardo Iachizzi, 20. Giovanni Pettinelli, 21. Alessandro Fusco, 22. Luca Morisi, 23. Tommaso Allan
Ireland promote six from the bench
Ireland have made six changes for Saturday's Six Nations trip to Italy, with each of those players having come off the bench to see off France last time out in a victory that made the world's top-ranked team championship favourites.
With captain Johnny Sexton absent due to a leg injury, Ross Byrne earns a well-deserved start at flyhalf. He will be partnered by Craig Casey, who is also set to start a Six Nations game for the first time as Conor Murray drops to the bench.
Peter O'Mahony and Stuart McCloskey also move to the bench to make way for Jack Conan and Bundee Aki, while Iain Henderson comes in at lock for Tadhg Beirne who suffered a tournament-ending ankle injury in the 32-19 win over France.
Rob Herring is continuing graduated return-to-play protocols after suffering a concussion against the French, but coach Andy Farrell's first-choice hookers are fully fit again with Ronan Kelleher starting and Dan Sheehan among the replacements.
Ireland, who remain without Robbie Henshaw, Tadhg Furlong, Jamison Gibson-Park and Cian Healy due to injury, top the standings on points difference ahead of Scotland after two matches. Italy are second-bottom in the table.
The two sides meet in Edinburgh on March 12, following Scotland's trip to France on Sunday.
Ireland team:
15. Hugo Keenan, 14. Mack Hansen, 13. Garry Ringrose, 12. Bundee Aki, 11. James Lowe, 10. Ross Byrne, 9. Craig Casey; 1. Andrew Porter, 2. Ronan Kelleher, 3. Finlay Bealham, 4. Iain Henderson, 5. James Ryan, 6. Caelan Doris, 7. Josh van der Flier, 8. Jack Conan
Replacements:
16. Dan Sheehan, 17. Dave Kilcoyne, 18. Tom O'Toole, 19. Ryan Baird, 20. Peter O'Mahony, 21. Conor Murray, 22. Jack Crowley, 23. Stuart McCloskey
