In the 1958–1959 season, Whitney had a co-starring role as Buck Sinclair, a former sergeant of the Union Army, in all 39 episodes of the ABC Western series The Rough Riders.

[3] He played United States Secret Service agent Gunnerson in the episode "Savage Hills," and Brock in "Dodge City or Bust" on the ABC/WB series, Maverick.

In 1960, in the episode "Surface of Truth" of another ABC/WB Western series, Lawman, Whitney played Lucas Beyer, a crude white man who has lived for ten years with the Cheyenne Indians.

Then, in 1965, Whitney was cast as Judge Roy Bean in the episode "A Picture of a Lady" on the syndicated television series Death Valley Days.

Peter Whitney's final role on television was that of a grave robber in writer Rod Serling's series Night Gallery, in a 1972 episode segment titled "Deliveries in the Rear".