Boatman was born in Colorado Springs, Colorado, the son of Gwendolyn Boatman Pugh, a job supervisor for the handicapped, and Daniel Boatman, an army officer. He was raised in Chicago. Boatman is a graduate of Western Illinois University and received its "Alumni Achievement Award" in 1997.
Boatman studied acting at Western Illinois University, where he played a variety of roles including Oberon in A Midsummer Night's Dream, and Purlie in Purlie Victorious. He was a member of the student sketch comedy troupe Shock Treatment, which performed at local bars and nightclubs. During his senior year Boatman won the prestigious Irene Ryan theater award for best supporting actor during the finals competition at the Kennedy Center.
In 1986, Boatman moved to Chicago, where he studied acting with Jane Brody, a popular acting teacher and casting director. Later that same year, he auditioned for and won the role of "Motown" in the critically acclaimed Vietnam action drama, Hamburger Hill. That same year he appeared in Running on Empty with River Phoenix, and The Trial of Bernard Goetz for the PBS American Playhouse series. In 1988, he auditioned for the pilot episode of the Vietnam era television drama, China Beach. He went on to play Samuel Beckett, the mortician in the China Beach mortuary, for the next three seasons. He later co-starred on The Jackie Thomas Show with Tom Arnold, and the short-lived WB series Muscle. In 1996, he landed a role on the ABC sitcom, Spin City, playing "Carter", the irascible, openly gay minority affairs liaison. For his work on Spin City he was nominated for five NAACP Image Awards for Best Supporting Actor in a Comedy. He also won the GLAAD (Gay and Lesbian Association Against Defamation) award for Best Actor.
At the same time he was on Spin City, Boatman played the role of "Stanley Babson", the anal-retentive chief financial officer on the HBO original series Arliss and starred on both series simultaneously until they were canceled in 2002. For his work on Arliss Boatman was nominated for four Image Awards, also for Best Supporting Actor. He played the lead role in the critically acclaimed Charles Burnett drama, The Glass Shield. Later, he appeared in the feature films The Peacemaker, with George Clooney and Nicole Kidman, and Woman Thou Art Loosed, and in several made-for-TV movies. Michael Boatman also narrated in the WPA slave narratives in the HBO film Unchained Memories, in 2003.
In 2007, Boatman co-starred in the feature films, The Killing of Wendy (2008), American Summer and My Father's Will. He has had many notable guest appearances, including five episodes of Law & Order: Special Victims Unit, Less Than Perfect, Yes, Dear, Scrubs, CSI: Miami, Hannah Montana and Grey's Anatomy. Boatman guest starred in the mystery/drama Warehouse 13, in July 2009.
In 2009, he joined the cast of the Lifetime comedy series, Sherri, starring Sherri Shepherd. The series is based on Shepherd's life experiences as a divorced single mom, actress and stand up comedian. Boatman plays 'Doctor Randy Gregg', Sherri's son's pediatrician and Sherri's love interest.
More recently he has appeared as attorney Julius Cain in The Good Wife. In 2011, Boatman guest-starred as Russell Thorpe on Gossip Girl, along with Tika Sumpter, who played his daughter Raina. In 2012, Boatman became a recurring character in the FX original series Anger Management, reuniting with his former Spin City co-star Charlie Sheen as Sheen's next door neighbor Michael. Beginning in late September 2013, he began co-starring in Nick at Nite's new series, Instant Mom, alongside Tia Mowry-Hardrict.
Boatman is also a screenwriter and novelist. He sometimes writes in the splatterpunk horror genre. Splatterpunk is a divisive genre which offends as much as it entertains. Joe Lansdale praised his first collection with ""Michael Boatman writes like a visitor from hell. Someone out on short term leave for bad behavior. I love this stuff. He's one of the new, and more than promising, writers making his mark, and a dark and wonderful mark it is."
Many multi-author anthologies feature at least one of his short stories. They include Sick Things: An Anthology of Extreme Creature Horror, Until Someone Loses an Eye, Sages and Swords, Badass Horror and Christmas in Hell. He has been published in Weird Tales, Horror Garage and Red Scream. He introduced Cyber-Pulp Halloween 3.0 which was published by Cyber-pulp Books. His Born Again from Eulogies II: Tales From the Cellar received an Honorable Mention from Ellen Datlow in The Best Horror of the Year: Volume Six. His first collection of short stories, God Laughs When You Die, was published by Dybbuk Press on October 23, 2007. His humorous horror novel, The Revenant Road, was published by Drollerie Press in 2009.