It was on television that Lambert played his biggest roles. He acted on 300 shows and appeared fourteen times on CBS's Playhouse 90anthology series, more than any other actor.[2] He appeared twice in the role of Yates in the 1962 syndicated adventure series The Everglades with Ron Hayes. Lambert was a frequent guest star on 1960s television (including roles Gunsmoke, and in Gene Barry's TV Western Bat Masterson, in 1959 as unscrupulous financier Charles Hamilton in the episode "Flume to the Mother Load", and in 1960 as the crooked Augustus Ulbrecht in "The Rage of Princess Ann") and was able to maintain a successful career into the 1990s.
Lambert was often able to secure billing that eluded his contemporaries, such as the coveted title-sequence billing he received both times he appeared on The Man From U.N.C.L.E., in "The Bow-Wow Affair" (1965) and "The Take Me To Your Leader Affair". He played a doctor in the 1960 Twilight Zone episode "King Nine Will Not Return". He also appeared in three episodes of the CBS courtroom drama series Perry Mason, twice in 1961: as Ben Nicholson in "The Case of the Envious Editor", and as murdered news correspondent Lawrence Vander in "The Case of the Renegade Refugee". He also appeared as Del Compton in the 1965 episode, "The Case of the Mischievous Doll". He was recognized for playing the French-Canadian revolutionary Durain in The Wild Wild West episode "The Night of the Firebrand". He appeared in a 1973 Barnaby Jones episode titled, "Sing a Song of Murder".[3]