Gilliard made his acting debut in an independent movie, Straight Out of Brooklyn, playing the lead role of Dennis Brown, in 1991. After a couple of years, he appeared in the movie Paul Mazursky The Pickle, where he shared screen along with Ally Sheedy and Jerry Stiller.
In 1996, Gilliard appeared in comedy movie by Donald Petrie, The Associate, along with Whoopi Goldberg. Later, he featured in an American epic period drama movie, Gangs of New York. The movie was directed by Martin Scorsese and produced by Alberto Grimaldi.
Similarly, Gilliard appeared in numerous television crime dramas, including The Wire, New York Undercover, Law & Order, Homicide: Life on the Street, Kill the Poor, The Machinist, The Double, Would You Rather and Walk of Shame.
Recently, he appeared in an American drama television series; directed, created, and scripted by former police reporter David Simon. This series was released on the premium cable network HBO in the United States, on September 10, 2017.
Gilliard is an American by nationality and belongs to black ethnicity. He married his long-term girlfriend, Michelle Paress after dating her for a long time. The couple has no any children yet. He lives a happy married life along with his wife and there is no any rumor of the couple's divorce.
Gilliard collects a tremendous amount of money through his professional career. His movie, Walk of Shame made a collection of $7.9 million at the box office and Gangs of New York, made a collection of $193 million, from where he must have collected the good bonus.
He collects a decent amount of salary and has a collection of cars of various brands and expensive house. According to some source, his net worth is estimated more than $2 million.