In 1961 he made his feature-film debut[3] in the 20th Century Fox comedy–fantasy The Two Little Bears, in which he co-starred with Eddie Albert and Jane Wyatt.

[3][4] Over the next two years, Patrick went on to appear in guest-starring roles on numerous television series, including Ben Casey, Alcoa Premiere, Bonanza, My Favorite Martian, Gunsmoke, Mister Ed, and Rawhide and recurring roles on The Real McCoys and General Hospital.

[5][6][7][8] These roles would have him appear opposite headliners including Judy Garland, Burt Lancaster, and Sidney Poitier.

"[8] Living on the East Coast at the time, Patrick commuted to Los Angeles every week during filming of the series, appearing in 70 episodes during The Munsters' two-season run from 1964 to 1966.

"[11] After The Munsters ended, Patrick continued to appear in guest-starring roles on various popular television series of the 1960s, including I Dream of Jeannie, Death Valley Days, Gunsmoke , The Monkees, Daniel Boone, and Adam-12, as well as a recurring role as Gordon Dearing on the CBS family comedy series My Three Sons.

In 1971, Patrick landed the starring role on Sid and Marty Krofft's Saturday morning children's program Lidsville, broadcast on ABC.

[10][14] In the psychedelic fantasy series, Patrick portrayed Mark, a boy lost in a strange land of walking, talking, singing hats, opposite veteran character actors Charles Nelson Reilly and Billie Hayes.

[19] In addition to his music, Patrick returned to occasional film and television work, including making cameo appearances as "Himself" on episodes of the Fox animated television series The Simpsons and the 2003 comedy film Dickie Roberts: Former Child Star, as well as appearing as a grown-up Eddie Munster in a Little Caesars Pizza commercial.

Patrick made a cameo appearance in the 2005 retro-horror film Frankenstein vs. the Creature from Blood Cove, directed by William Winckler, playing a man who had become a werewolf, speaking a line of dialogue in comical reference to The Munsters.