She made her big screen debut in the Western film Pale Rider directed by Clint Eastwood.

Walker during the final season of NBC soap opera Santa Barbara (1992–1993), receiving Daytime Emmy Award for Outstanding Younger Actress in a Drama Series nomination.

She later joined the cast of ABC soap opera All My Children (1993–1997, 2002-05, 2008) playing the role of Julia Santos Keefer receiving Daytime Emmy Award for Outstanding Supporting Actress in a Drama Series nomination in 1995.

[2] She made her screen debut playing the supporting role in the made-for-television movie The Night Rider (1979) starring David Selby, Kim Cattrall and Hildy Brooks.

[4] In 1985, she starred as Megan Wheeler in the Western film Pale Rider directed by Clint Eastwood, released on June 26, 1985.

[9] She played the role of Julia Santos Keefer on the ABC soap opera All My Children, from 1993 to 1996, with guest appearances in 1997 and 2002 and returned to the show in 2005.

In 1999 she took the role of Meg Cummings in the NBC soap opera Sunset Beach replacing Susan Ward for one month during her filming the movie The In Crowd.

The serial's creator, Aaron Spelling, was impressed with Penny's portrayal of Meg so he cast her in another series he created.

[13] She starred in the number of movies for Hallmark Channel and Lifetime, notable Hidden Places (2006), The Wife He Met Online (2012) and Killer Crush (2015).