[10] Van Ark began her professional career at the Guthrie Theater in Molière's The Miser and appeared opposite Hume Cronyn and Zoe Caldwell.

After a season at the Arena Stage in Washington, D.C., she originated the role of Corie in the national touring company of Barefoot in the Park, directed by Mike Nichols.

In 1971, she revisited Broadway, where she earned a Theatre World Award and received a Tony nomination (Best Featured Actress in a Play) for her performance as Agnès in Molière's The School for Wives, directed by Stephen Porter.

After receiving a contract with Universal Studios, Van Ark co-starred with Bette Davis in The Judge and Jake Wyler, a 1972 two-hour telefilm and series pilot that failed to be picked up by NBC.

Van Ark played the role of Erika in M*A*S*H in 1973 in the episode entitled "Radar's Report,” in which she rejects the prospect of marriage to Hawkeye (Alan Alda).

In 1974, Van Ark, tapped as a late replacement for Mary Ure, returned to Broadway as Silia Gala in a revival of Pirandello's The Rules of the Game, which was performed by the New Phoenix Repertory Co. at the Helen Hayes Theater and also featured Glenn Close, who, in addition to playing a bit part as a neighbor, served as Van Ark's understudy in the lead role of Silia.

[14] Van Ark co-starred opposite Richard Boone in the science fiction outing The Last Dinosaur, which was filmed at Tsuburaya Studios in Tokyo and on location in the Japanese Alps.

Her character was married three times to husband Gary Ewing, played in the series by Ted Shackelford; and during the show's run, also had two other marriages: to Ben Gibson (Doug Sheehan) and Danny Waleska (Sam Behrens).

During her thirteen years on Knots Landing, Van Ark earned two Soap Opera Digest Awards for Best Actress (1986, 1989) and was nominated an additional six times.

Over the course of the program, Van Ark probably received her greatest recognition as an actress during the sixth year, which featured an intricate storyline involving the theft of Valene's twin babies.

Their disappearance (and alleged stillborn deaths) provoked Valene to embark on a surreal spiritual journey and pilgrimage in which she left the cul-de-sac in California and morphed into the persona of a character from a novel she had written.

"[19] - Joan Van Ark This dark, gripping tale earned Knots Landing its only placement ever on Nielsen's annual Top 10 programs list.

In the 1984–1985 season finale, "The Long and Winding Road," Val finds out that her babies are still alive, and this episode's original broadcast on May 23, 1985, also marked the only time Knots Landing ever reached the #1 spot in the weekly Nielsen ratings.

[20][21] In its edition dated June 29, 1985, TV Guide assessed of her performance: "Knots Landing has the grimmest plots but the strongest cast, headed by the incomparable Joan Van Ark as Valene.

In 1985, she also co-hosted with Bob Barker CBS' Tournament of Roses Parade, which received a Daytime Emmy nomination for Outstanding Special Class Program.

Shortly before leaving Knots Landing, she starred opposite Christopher Meloni in an ill-fated pilot called Spin Doctors, a sitcom for NBC that was not picked up.

In 1997, Van Ark also directed a documentary short on homelessness and domestic violence for the Directors Guild of America, and the piece was nominated for an Emmy Award.

Van Ark has also starred in three Williamstown Theatre Festival productions: The Night of the Iguana (1987),[23] the 40th anniversary presentation of Stephen Sondheim's A Little Night Music (1994) [24] and The Legend of Oedipus (1988), which is a five-hour, two-part adaptation by Kenneth Cavander of the classic Greek tragedies and was directed by WTF co-founder Nikos Psacharopoulos,[25][26] who was also Van Ark's acting professor when she was attending the Yale School of Drama.

[citation needed] On February 1, 1966, Van Ark married news reporter John Marshall, who later became a correspondent for two decades at KNBC-TV and won both an Emmy and a Golden Mike Award.