Merkerson's many nominations for the play included ones for a Tony, a Drama Desk and the L.A. Theater Critics Award. She won an OBIE for a later New York stage appearance in "I'm Not Stupid" (1992) and also found small roles in features coming her way. After a debut in the comedy "Loose Cannons" (1989), Merkerson also played in the striking horror feature "Jacob's Ladder" (1990) before essaying her best-known feature role to date, the screaming wife of Joe Morton in the mega-hit "Terminator 2: Judgment Day" (1991). Television, however, gave her more substantial parts with which to work. In addition to TV-movies including "A Place for Annie" (1994), Merkerson found her articulate, unglamorous appeal in demand for a role as Lieutenant Anita Van Buren on the acclaimed NBC drama series, "Law & Order,” which she joined in 1993. She reprised her character on episodes of the ever-persistent spin-offs “Law & Order: Criminal Intent” (NBC, 2001- ) and “Law & Order: Trial By Jury” (NBC, 2004-2005).

While continuing to guest star on television series, including episodes of “South Beach” (NBC, 1993) and “Fraiser” (NBC, 1993-2004), Merkerson maintained a steady presence in feature films and movies-of-the-week. After playing a caustic, but compassionate nurse caring for an HIV-positive mother and widow (Linda Hamilton) in “A Mother’s Prayer” (USA, 1995), she appeared in “Breaking Through” (ABC, 1996), a maudlin drama about a deaf girl (Kellie Martin) who, thanks to a dedicated abuse counselor (JoBeth Williams), is given a new lease on life after being kept a virtual prisoner in her home since age six. In the stale drama, “An Unexpected Life” (USA, 1998), the sequel to 1996’s “An Unexpected Family,” Merkerson tried in vain to add zest to the proceedings as a school principal from Harlem. That same year, she once again revived her role of Lieutenant Van Buren for “Exiled: A Law and Order Movie” (NBC).

Merkerson switched back to feature films, appearing briefly in “Random Hearts” (1999), a romantic drama about two Washington D.C. insiders (Harrison Ford and Kristen Scott Thomas) who discover their spouses were having an affair after their deaths in a plane crash. She then played the loving mom of a mentally disabled man (Cuba Gooding, Jr.) who is brought out of his loner existence by a small town football coach (Ed Harris) in the sentimental drama, “Radio” (2003).

After playing a doctor in Kevin Smith’s overlooked “Jersey Girl” (2004), Merkerson played Nanny, a vibrant woman who runs a lively boarding house, in “Lackawanna Blues” (HBO, 2005), an adaptation of Ruben Santiago-Hudson’s Obie award-winning play. Nanny becomes the primary caregiver of a young boy, Rueben Jr. (Marcus Carl Franklin), who was left at the boarding house by his working mother. In her role, Merkerson emanated joy despite the hardship suffered by her character, giving the young boy hope that good will can come from misfortune. Her performance earned Merkerson an Emmy for Outstanding Lead Actress in a Miniseries of Movie. In her acceptance speech, Merkerson had the biggest laugh on an otherwise dull evening when she lost her list of people to thank down the front of her dress where she put it for safe keeping. She also won a Golden Globe award for Best Performance by an Actress in a Mini-Series or a Motion Picture Made for Television.

Merkerson moved on to costar in the Tennessee-set “Black Snake Moan” (2007), a character-driven drama about Lazarus Woods (Samuel L. Jackson), a down-and-out, God-fearing ex-blues singer who finds Rae (Christina Ricci), a young sexually abused woman, beaten unconscious in a ditch. After learning that Rae is routinely used by every man in town, leading her to engage in wanton sex as means to stave off fear and loneliness, the old blues singer chains her to his radiator in order to save her soul, through which he hopes to find his own redemption. Merkerson played the town’s pharmacist who is routinely charmed by Lazarus for medicine and is ultimately the focus of his renewed interest in love.