Walden is also well known for his roles in the films Blue Sunshine, The Hospital, All the President's Men, Audrey Rose, and Capricorn One.
Walden first became interested in acting while attending City College of New York, and shortly thereafter became a member of the Actors Studio.
[5] MTM producers James L. Brooks and Allan Burns "discovered" Walden when he played the role of police officer Ernie Joyce on the Mary Tyler Moore spin-off show Rhoda in an episode that aired in January 1977.
[7] He was a cast member on Lou Grant during its entire run (1977–1982), and received three Emmy Award nominations (in 1979, 1980 and 1981) for Outstanding Supporting Actor in a Drama Series for the role.
In August, 2006 he appeared in the Herbert Berghof Playwrights Foundation (HB Studio) production of Arthur Miller's The American Clock under the direction of Austin Pendleton.