BAD boy Robert Downey Jr. has inked a deal to appear on eight more episodes of “Ally McBeal” taking him through the end of the season.

Downey, who’s battled drug problems and spent a year in the slammer for drug use, agreed to continue his role as Larry Paul – the lover of waifish Boston attorney Ally McBeal (Calista Flockhart) on the Fox dramedy.

Downey’s eight-episode commitment will bring his total “Ally” episodes up to 18 for the season.

“Working on ‘Ally McBeal’ has been such a satisfying process that I am grateful to have been asked to continue on for the remainder of the season,” Downey said in a statement.

Downey has won a Golden Globe for his work on “Ally McBeal” and has been nominated for a Screen Actors Guild Award and TV Guide Award.

Thanks in large part to Downey, “Ally’s” viewership is up 3 percent over last season and the show seems to be re-energized.

Downey, 35, made his “Ally McBeal” debut on Oct. 23, several months after being released from prison.

The one-time Oscar nominee (“Chaplin”) was busted last Thanksgiving for allegedly possessing cocaine and Valium and charged with a misdemeanor of being high when cops arrested him.

Downey’s next appearance on “Ally” will be in the Feb. 26 episode.