Early in his career, Evans was best known for his television career including playing "Darien" on 17 episodes of the CBS sitcom Cosby from 1998 until 2000, and as “Dr. Fields” on the NBC drama Third Watch in 22 episodes from 2002 until 2005. Other guest appearances include Law & Order, New York Undercover, Law & Order: Special Victims Unit, The Black Donnellys, and Person of Interest. More recently, he played "Darnell Nichols" on 8 episodes of Treme between 2011 and 2013.
Sills-Evans wrote, directed and starred in the 2002 film X-Patriots, a romantic comedy about two black American men who travel to the Netherlands – a place where no one looks like them – in search of self-identity. X-Patriots was named Best Feature Drama and a Critic's Choice at the Angelciti Film Festival in Chicago, and an official selection at the Boston Film Festival, the Newark Black Film Festival and the Sidewalk Film Festival. He financed the film with money he earned from his appearances on Cosby.
In 2005, Sills-Evans was associate Producer and starred in The Reception directed by John G. Young which had its world premiere at the Tribeca Film Festival. The film subsequently played at numerous festivals in the U.S., including Outfest in Los Angeles, where Sills-Evans earned a best actor award.
In 2009, co-wrote and produced the feature film Rivers Wash Over Me directed by John G. Young (of The Reception). The film became the centerpiece movie of the 2009 NewFest Festival. At the 2009 Outfest in Los Angeles, the leading role actor Derrick L. Middleton in the movie won the Grand Jury Award for "Outstanding Actor in a Feature Film". Darien Sills-Evans also appears in the film in the role of Charles King.
Sills-Evans has appeared in comedy venues across the United States. In 2010 he founded Tipsy Hustle, a comedy show and open mic that continues at The Five Spot Soul Food Restaurant in Brooklyn, New York and at The Improv Space in Los Angeles.
Since at least 2011, Evans has been the national spokesperson for U.S. Cellular.
In 2014, Sills-Evans began production on RaceMan, a weekly podcast that features comedians - usually persons of color - discussing newsworthy events and pop culture.
