Eckholdt began his screen career in the mid-1980s. He began with appearances on TV shows like The Love Boat and 21 Jump Street. He landed recurring roles on WIOU (a short-lived CBS series in 1991) and Life Goes On. His main screen appearances include L.A. Law, Melrose Place, It's Like, You Know..., Providence, The West Wing and The L Word.
In the 1986 film The Wraith Eckholdt played the character George in the films opening sequence.
He appeared as Mark Robinson, a co-worker (and according to Ross, lover) of Rachel Green (Jennifer Aniston) in the sitcom Friends. His role in the 1997 TV pilot for the sitcom Dads is seen by test audiences at the Television Preview, a marketing research operation in which participants are told they are seeing a pilot for a new program. In 1997, Eckholdt also appeared in "The Puppy Episode" of Ellen, and in The Practice.
He starred as Peter Albright in Santa Who (2000), a TV movie featuring Leslie Nielsen.
In 2003, Eckholdt starred in the CBS television sitcom My Big Fat Greek Life which was based on the blockbuster comedy feature film, My Big Fat Greek Wedding. He starred as Thomas Miller, the character originally portrayed as Ian Miller by John Corbett in the movie version. In 2003 he appeared in Secret Santa with Jennie Garth. In 2003 he appeared in Comfort and Joy with Nancy McKeon. In 2008 he appeared in Our First Christmas with Julie Warner and Dixie Carter.
In 2010, he appeared in the seventh season of Two and a Half Men as Brad, a Lawyer who causes the breakup of Charlie and Chelsea.
