Auburn-haired Arleen Whelan was born in Salt Lake City, but spent her early childhood in Pueblo, Colorado, where she attended High School. Her father, an electrician, opened his own electrical store in Los Angeles, prompting the family to make the westward move. Arleen enrolled in a beauty college, learning hairdressing and manicure, and soon found work for $18 a week in a salon on Hollywood Boulevard. It was there that she was discovered by director H. Bruce Humberstone, who suggested her name to Darryl F. Zanuck, leading to a seven-year contract with 20th Century Fox in May 1937.
Within a year, Whelan had her first co-starring assignment opposite Warner Baxter in the 1938 film Kidnapped. She then landed the highly prized role of pioneer woman Hannah Clay in Young Mr. Lincoln (1939),and by 1942, she made the jump to Broadway, appearing as one of "The Doughgirls" alongside Virginia Field and Doris Nolan. Although she was not cast in the 1944 film version of "The Doughgirls," which starred Jane Wyman, Hollywood's publicity machine capitalized on her high-profile affair with actor Tyrone Power.
In 1945, Whelan was voted "the most perfect all-over beauty" by a panel of magazine illustrators, but her career was already beginning to wane. Out of contract and dissatisfied with her roles, Whelan left Hollywood to live with her second husband, a Paramount executive, in New York. However, her stay was short-lived, and the marriage was ultimately unsuccessful.
Whelan continued to work as a freelance actress, appearing in the 1947 film The Senator Was Indiscreet, in which she played the role of busybody Valerie Shepherd, earning a "cute" review from critic Bosley Crowther in the New York Times. She also starred opposite Charles Winninger in director John Ford's The Sun Shines Bright (1953),which remains one of Ford's favorite films.
For the remainder of her career, Whelan appeared in a series of B-westerns, including those made for Republic and Albert C. Gannaway's independent production company. Eventually, Whelan left the screen in 1957 to focus on her impressive golf handicap.