Ally Walker made her television debut in the NBC daytime soap opera, Santa Barbara (1988), before landing the leading roles on the short-lived dramas True Blue (1989–1990), and Moon Over Miami (1993).
During the 1990s, Walker had roles in films such as Universal Soldier (1992), Singles (1992), When the Bough Breaks(1994), While You Were Sleeping (1995), Kazaam (1996), and Happy, Texas (1999). From 1996 to 1999, she played the leading role as Doctor Samantha Waters on the NBC crime drama series Profiler, for which she received Saturn Award for Best Actress on Television nomination. She returned to television with role in the HBO drama series Tell Me You Love Me (2007), and later played villainous Agent June Stahl in the FX crime drama, Sons of Anarchy, (2008–2010). Walker also had the leading role in the short-lived Lifetime police drama series The Protector in 2011. During Seasons 4 and 5 (2014 and 2015) of Longmire, she played Dr. Donna Monaghana, a therapist treating veterans who is the title character's love interest.