In 2005, O'Neal began a recurring role as Maggie Gavin in the firehouse drama series Rescue Me, portraying the unbalanced and lively sister of Tommy Gavin, played by Denis Leary.
Fra 2005 har O'Neal jævnligt spillet rollen som Maggie Gavin i dramaserien Rescue Me, der skildrer den ustabile og livlige søster til Tommy Gavin, spillet af Denis Leary.