Rupert Grint will follow in the Broadway footsteps of fellow “Harry Potter” star Daniel Radcliffe this fall, with Grint signing on for the already starry production of Terrence McNally’s “It’s Only a Play.”

Grint, who made his London stage debut last year in the West End revival of “Mojo,” will appear in “It’s Only a Play” with an ensemble headlined by the Broadway return of Nathan Lane and Matthew Broderick — the duo who helped make “The Producers” into a Main Stem smash — and filled out with Megan Mullally, Stockard Channing and F. Murray Abraham, as well as newbie Micah Stock. Jack O’Brien, the “Hairspray” helmer whose staging of “Much Ado About Nothing” just opened in Central Park, directs.

For an actor closely associated with a global franchise such as “Harry Potter,” a legit engagement on Broadway can help broaden the perception of a thesp’s talents while also allowing the actor to hone new skills. That was certainly part of the appeal for Grint’s “Potter” co-star Radcliffe, now in the midst of his third Broadway run, appearing in “The Cripple of Inishmaan” after stints in “Equus” and “How to Succeed in Business Without Really Trying.”

As evidenced by the middling sales of the well-received revival of “Inishmaan,” a starring turn by a “Harry Potter” thesp doesn’t necessary guarantee a box office bonanza. But “It’s Only a Play” looks to have assembled a critical mass of headturning actors, with the Lane-Broderick pairing alone seeming likely to drive traffic.

The new staging of McNally’s 1982 backstage comedy centers on a playwright (Broderick) waiting for his latest batch of reviews with a TV star (Lane), a producer (Mullally), his lead actress (Channing), his director (Grint) and a critic (Abraham). McNally’s newest play, “Mothers and Sons,” is currently wrapping up a Broadway run that ends June 22.

Produced by Tom Kirdahy, Roy Furman and Ken Davenport, “It’s Only a Play” is set for an Oct. 9 opening at the Schoenfeld Theater, where “The Bridges of Madison County” ended its run last month.