Fellowes work in musical theater includes his book for the stage musical version of Disney's Mary Poppins. He won an Oscar for his original screenplay to Gosford Park. He also won Emmy and Golden Globe Awards for Downton Abbey.

Based on the memoirs of Gypsy Rose Lee, the musical Gypsy features a book by Arthur Laurents, music by Jule Styne, and lyrics by Stephen Sondheim.