Shaiman started his career as a theatre/cabaret musical director. He then became vocal arranger for Bette Midler, eventually becoming her musical director and co-producer of many of her recordings, including The Wind Beneath My Wings and From a Distance. He helped create the material for her Emmy Award winning performance on the penultimate Tonight Show with Johnny Carson. His work with both Bette Midler and Billy Crystal led to his involvement on their films.
His film credits include Broadcast News, Beaches, When Harry Met Sally..., City Slickers, The Addams Family, Sister Act, Sleepless in Seattle, A Few Good Men, The American President, The First Wives Club, George of the Jungle, In & Out, Patch Adams, South Park: Bigger, Longer & Uncut, Team America: World Police and HBO's From the Earth to the Moon, and 61*. He frequently works on films by Billy Crystal, Rob Reiner, and Trey Parker He has also appeared in many of these films.
Shaiman has earned five Academy Award nominations, a Tony Award and a Grammy Award for his work on the musical Hairspray, and an Emmy Award for co-writing Billy Crystal's Academy Award performances. He has also been Grammy nominated twice for his arrangements for Harry Connick Jr.'s recordings When Harry Met Sally... and We Are in Love and Emmy nominated for his work on Saturday Night Live. In 2002, he was honored with the "Outstanding Achievement in Music-In-Film" award at The Hollywood Film Festival, and in 2007 he was honored with ASCAP's Henry Mancini Award in recognition of his outstanding achievements and contributions to the music of film and television. He is the first recipient of the Film & TV Music Award for Best Score for a Comedy Feature Film.
Fans of Saturday Night Live may recognize Shaiman as Skip St. Thomas, the accompanying pianist for The Sweeney Sisters, a singing duo played by Nora Dunn and Jan Hooks. He began his professional relationships with Billy Crystal and Martin Short during his tenure at SNL. He wrote and sang a song for his agent's film Finding Kraftland; the song was called Yes.
To protest the passage of California Proposition 8 in November 2008, Shaiman wrote a satiric mini-musical called "Prop 8 — The Musical". The 3-minute video was was distributed on the internet at FunnyOrDie.com beginning on December 3, 2008. It was written and produced in just a few days. The cast includes Jack Black (who plays Jesus), Neil Patrick Harris, John C. Reilly, Allison Janney, Andy Richter, Maya Rudolph, Margaret Cho, Rashida Jones and other celebrities. Shaiman plays the piano and appears briefly on the video. It received 1.2 million internet hits in its first day