A right fielder and a powerful left-handed hitter, Kirkland appeared in 1,149 games in Major League Baseball over nine seasons for the San Francisco Giants (1958–1960), Cleveland Indians (1961–1963), Baltimore Orioles (1964) and Washington Senators (1964–1966).

He won the regular right field job and appeared in the team's first-ever official game on the West Coast: an 8–0 thrashing of the Los Angeles Dodgers at Seals Stadium on April 15.

[2] Kirkland was part of a flood of young players who joined the Giants during their maiden years in San Francisco (others included Felipe Alou, Orlando Cepeda, Jim Davenport, Juan Marichal, Willie McCovey and Leon Wagner), and he went on to hold the Giants' regular right-field job for three seasons, through 1960, belting 57 home runs and hitting .261.

But after the 1960 season, the Giants traded Kirkland to the Cleveland Indians with veteran pitcher Johnny Antonelli for outfielder Harvey Kuenn.

Kirkland spent the rest of his major-league career with Washington as a backup outfielder before he was assigned outright to the Triple-A Hawaii Islanders of the Pacific Coast League.