The pair split in 2010 and went through a bitter court battle to decide custody rights over their daughter Lucia.
In 2011, a deal was finally agreed, with the warring couple sharing custody of the tot and Gibson handing the Russian singer a one-off payment of $750,000 (£468,750), as well as a house until Lucia turns 18.
However, Grigorieva is unhappy with the way her lawyers conducted the case, and has now filed suit, claiming Ron Litz and Daniel Horowitz gave her bad advice when it came to her settlement.
In the documents, filed in Los Angeles by Grigorieva herself, she states that the settlement she signed prevents her from pursuing further legal action against Gibson without jeopardising the lump sum she was awarded, and that she also has no ownership rights over the home she shares with her daughter.
Grigorieva is seeking unspecified damages.