Christopher reached the big leagues with the 1959 Pittsburgh Pirates, spending three years there before moving to the New York Mets (1962–65) and Boston Red Sox (1966).

While in Pittsburgh, Christopher was used as a backup in all three outfield positions for Bob Skinner (LF), Bill Virdon (CF), and Roberto Clemente (RF).

Christopher had a career-best day on August 19, collecting two triples, a double, and a home run in an 8–6 victory over his former Pirates teammates.

[1] In June 1966, the Red Sox traded Christopher with pitcher Earl Wilson to the Detroit Tigers, who sent Julio Navarro as part of the package.

[2] An interesting event that occurred during the 1958-1959 Puerto Rican Winter League campaign was Christopher getting beaned in the helmet by a pitch from Ruben "El Divino Loco" Gomez Colon of the Cangrejeros de Santurce causing a near riot by irate Mayaguez fans who overturned Gomez's red corvette after the game and were inconsolable even after Christopher attempted to calm the crowd over the PA system.