Michael K. Williams made his debut in the 1996 American crime drama film ‘Bullet’ where he played the role of ‘High Top.’ In 1999, he starred in the American psychological drama film ‘Bringing Out the Dead’ directed by Julien Temple. While the film received mostly positive reviews from critics, it failed to achieve success at the box office. He next appeared in television series like ‘Law & Order’ (2001), ‘Deadline’ (2001), ‘The Sopranos’ (2001), and ‘Third Watch’ (2002). In 2002, he joined the cast of the American crime drama television series ‘The Wire’ created by David Simon. He played the role of ‘Omar Little’ and remained a part of the series until it went off-air in 2008. He continued to star in television series and films such as ‘Law & Order: Special Victims Unit’ (2003), ‘Lackawanna Blues’ (2005), ‘Alias’ (2005), ‘Boston Legal’ (2005), ‘Six Degrees’ (2006-2007), ‘The Kill Point’ (2007), ‘Human Giant’ (2008), ‘CSI: NY’ (2008), ‘Law & Order’ (2009), ‘The Philanthropist’ (2009), and ‘CSI: Crime Scene Investigation’ (2010). In 2010, he became a part of the American period crime drama television series, ‘Boardwalk Empire’ created by Terence Winter. He portrayed Albert "Chalky" White in the series which earned a ‘Screen Actors Guild Award’ (shared with the cast). Boardwalk Empire ran for 5 seasons and aired its final episode in 2014.
He was next seen in television series and shows such as ‘Detroit 1-8-7’ (2011), ‘Aqua Teen Hunger Force’ (2011), ‘Community’ (2011-2012), ‘Walk This Way’ (2013), ‘High School USA!’ (2013), ‘Lucas Bros. Moving Co.’ (2014), and ‘I Love the 2000s’ (2014). In 2014, Williams received a Primetime Emmy Award nomination for his performance as Jack Gee in the HBO TV film ‘Bessie’ directed by Dee Rees. The film received positive reviews from critics and scored a 90% approval rating on Rotten Tomatoes. In 2016, he played the role of ‘Freddy Knight’ in the American eight-part crime drama television miniseries ‘The Night Of’ which again earned him a Primetime Emmy Award nomination. He next appeared in television series and shows like ‘Black Market with Michael K. Williams’ (2016, 2022), ‘Hap and Leonard’ (2016-2018), ‘When We Rise’ (2017), ‘F Is for Family’ (2017-2021), ‘The Guest Book’ (2018), ‘Last Week Tonight with John Oliver’ (2019), ‘When They See Us’ (2019), and ‘Lovecraft Country’ (2020). He was last seen in the 2022 American thriller drama film ‘892’ (Posthumous release) directed by Abi Damaris Corbin.