Waldman was born in Chicago, Illinois on September 8, 1955. Waldman began playing piano at age five at which time he was considered a child prodigy. He was hired to demonstrate pianos at a local piano store at age 12. While in high school, he performed with the Northwestern University Jazz band.
At the age of 21, Waldman was hired to go on tour as the pianist for Frank Sinatra. He was then hired by The Lettermen to go on tour from Chicago to Los Angeles. After the tour, Waldman relocated to Los Angeles and, within a year, he toured with Minnie Riperton, Lou Rawls, Paul Anka, and George Benson, the last of whom kept Waldman around as his pianist, musical director, and arranger for the following seven years.
Eventually, Waldman began a session career in Los Angeles that would go on to span 40 years. He has performed on hundreds of albums, motion picture soundtracks, television shows, and jingles. In the 1980s, Waldman worked on soundtracks such as Ghostbusters, Romancing the Stone, Back to the Future, Nuts, Beetlejuice, Salsa, Who Framed Roger Rabbit, The Abyss, and Weekend at Bernie's.
In 1983, Waldman was nominated for a Grammy for Best Vocal Arrangement for The Manhattan Transfer's "Code of Ethics", from their album Bodies and Souls. Two years later, Waldman's co-arrangement of the West Side Story song "Somewhere", on Barbra Streisand's The Broadway Album, won a Grammy. Waldman has been Streisand’s pianist for over 30 years and is featured on many of her albums, movies, and live performances.
In the 1990s, Waldman worked on the soundtracks for numerous films including Forrest Gump, The Bodyguard, Mission: Impossible, and Titanic. He also worked with numerous artists over the course of his career including Barbra Streisand, Michael Jackson, Paul McCartney, Patti LaBelle, Celine Dion, Beyoncé, Madonna, Whitney Houston, Olivia Newton-John, Barry Manilow, Ray Charles, The Stylistics, Michael Bublé, Quincy Jones, Johnny Mathis, Stevie Wonder, Andrea Bocelli, John Travolta, Kenny G, Katey Sagal, and others.
In 1998, Waldman released his first solo album, Wigged Out, on his own WhirlyBird Records, featuring bassist John Pattitucci and drummer Vinnie Colaiuta. The album consisted of a collection of classical songs reworked with jazz arrangements. His second album, UnReel, was released in 2001 and featured a variety of soundtrack and theme music from many different films and television shows. In 2002, he worked on the soundtrack for Ice Age before releasing a third album, Timing is Everything, in 2003.
In 2017, Waldman appeared on Seal's Standards album which featured some of Frank Sinatra's songs. He was also featured as Barbra Streisand's pianist, music director, and conductor for her Barbra: The Music, The Mem'ries, The Magic tour. A filmed version of one of the shows was released on Netflix in November 2017.