From 1972 to 1976 O'Loughlin appeared as Lt. Ed Ryker on "The Rookies". In 1978, he appeared in the pilot episode of "The Eddie Capra Mysteries", and had roles in TV miniseries such as "Wheels" (1978), "Women in White" (1979), "" (1979) and "Blind Ambition" (1979). He also appeared as Sgt. O'Toole in the 1983 made-for-TV miniseries "The Blue and the Gray". Also in 1983, he appeared as Gen. Schwerin, hoping to meet Marilyn Monroe, in the M*A*S*H Episode "Bombshells." He was also a regular the series "Automan" (1983) and "Our House" (1986). Also in 1986, O'Loughlin played the part of Mr. Parks in a first season episode of "Highway to Heaven" entitled "The Brightest Star".