She is known for her professional and personal relationship with choreographer Michael Bennett, with whom she collaborated on her most noted role, the character of Cassie in the musical A Chorus Line.

A stint in a Philadelphia production of A Funny Thing Happened on the Way to the Forum (as Philia) was followed by the NBC music series Hullabaloo, on which she was a featured dancer.

She also appeared as Philia in the national tour of Forum, starring Jerry Lester (Pseudolus), with Paul Hartman (Senex), Erik Rhodes (Marcus Lycus), Arnold Stang (Hysterium) and Edward Everett Horton (Erronius), produced by Martin Tahse.

Along with Baayork Lee and Margo Sappington, she danced in one of Broadway's most famous numbers, "Turkey Lurkey Time", which was when she first began to attract notice from critics and theatergoers alike.

The same year, in season 2 of the TV show Family Ties, she played Cynthia, a divorcee who planned to move west with her young son away from his father.

After her rise to fame, she made guest appearances on Scarecrow and Mrs. King (whose female lead, Kate Jackson, was also a Dark Shadows alumna), Rowan & Martin's Laugh In, and Cheers (as Debra, the ex-wife of Sam Malone).

In February, 1997, she played Phyllis in a concert performance of Follies at London's Drury Lane Theatre, and the following year took on the role of Sally in a production of that same show at the Paper Mill Playhouse in New Jersey.

McKechnie also starred opposite Carol Lawrence in the Los Angeles and New York production of Joni Fritz's Girl's Room, produced by Dennis Grimaldi and directed and choreographed by Lynne Taylor-Corbett, both former Michael Bennett dancers.

In recent years, she has toured periodically in her one-woman show Inside the Music, a potpourri of songs, dances and anecdotes about her life in the theater and her successful battle with arthritis, directed by her old Chorus Line castmate, Thommie Walsh.

Her autobiography, Time Steps: My Musical Comedy Life, written with Greg Lawrence, was published by Simon & Schuster on August 29, 2006, only weeks before the Broadway revival of A Chorus Line opened on October 5.