In 1980, Grahn made her daytime television debut on ABC's One Life to Live in the role of Beverly Wilkes, the secretary of Marco Dane. Grahn left the series in 1982.
In 1985, Grahn was cast on the NBC daytime soap opera Santa Barbara as headstrong attorney Julia Wainwright. A departure from the stereotypical "damsel in distress" or "vixen" roles, Julia was an intelligent and uncompromising woman. Paired with Mason Capwell (portrayed by Lane Davies), the two had a Spencer Tracy / Audrey Hepburn-esque romance. Grahn's performance garnered her a Daytime Emmy Award in 1989 for Best Supporting Actress. Grahn remained with series until its final episode aired on January 15, 1993.
In 1996, Grahn joined the cast of General Hospital in the role of Alexis Davis (born Natasha Cassadine), the illegitamate daughter of notorious 1980s General Hospital villain Mikkos Cassadine, where she has remained ever since.