Meiklejohn began his career in 1921 in his native Los Angeles as a booking agent for 80 different vaudeville acts. In 1939 he sold his agency to the Music Corporation of America (MCA) when the corporation opened in Hollywood and joined them as vice-president in charge of setting up their motion picture division. In 1940, he was loaned to Paramount for two weeks, but stayed for 20 years as head of talent and casting. In 1960, he left the studio and once again became an independent agent for the likes of Nat King Cole, Pat O'Brien, and his close friend Ronald Reagan.[1][2]
For contributions to the motion picture industry he was honored with a star on the Hollywood Walk of Fame at 1777 Vine Street.[5] the star is inscribed simply "Meiklejohn" as it was dedicated to not only William but also his siblings, sister Jean and brother Campbell. Jean ran the Meiklejohn and Dunn Theatrical agency which was located in the Majestic Theatre building in Hollywood, along with another brother Matthew. Campbell was manager of Grauman's Egyptian Theatre in Hollywood which held the first Hollywood premiere Robin Hood in 1922 the last one to be held at the Egyptian was Funny Girl in 1968.