The L Word actress will play Melody Patterson, the former wife of detective Vince Korsak (Bruce McGill), according to TV Line.
"I have always wanted to work with Lolita, and tailored this role for her," said the show's executive producer Janet Tamaro.
Davidovich has previously appeared in episodes of CSI, Criminal Minds and Curb Your Enthusiasm.
Her film credits include 1998's Gods and Monsters and 2002's Dark Blue. Earlier this year, she also signed up to star in TBS comedy pilot Hound Dogs but the project did not receive a series pick-up.
Her Rizzoli & Isles episode, 'Seventeen Ain't So Sweet', will air in December. The show was recently picked up for a 15-episode third season.
Rizzoli & Isles continues on Mondays at 10/9c on TNT.
> Rizzoli & Isles stars tease season two romances
Watch a promo for the next episode of Rizzoli & Isles below: