The 34-year-old has signed a one-year deal with the Championship side.
“The signing of Damiano adds great experience to the squad,” QPR boss Iain Dowie told their official website.
“He’ll complement what Gavin Mahon and Martin Rowlands provide in that area.
“He has played at the highest level for Club and country and to have a player of that calibre available can only be good for QPR.
“We’ve got some fantastic young talent in the squad, such as (Emmanuel) Ledesma, (Angelo) Balanta, (Daniel) Parejo and (Hogan) Ephraim, and training with someone of Damiano’s stature will be of huge benefit to them I’m sure.
“In the short term, he could prove to be very useful to us.”
Tommasi was released from Spanish side Levante at the end of last season.
