Between mid-1931 and 1936, Mailho played for the Oakland Oaks in the Pacific Coast League, hitting over .300 each year, except for an injury shortened 1934 season.

[1] When called up by the Athletics, Mailho was mostly used as a left-handed pinch hitter by manager Connie Mack, although he appeared in one game as an outfielder.

After his stint with the Athletics, Mailho joined the Atlanta Crackers of the Southern Association for the rest of the 1936 season, hitting .315.

Mailho returned to the Pacific Coast League, playing for the Oakland Oaks in 1942 to 1944, and the San Francisco Seals in 1945.

[1] Mailho ended his professional career with the Oklahoma City Indians of the Texas League in 1946, playing 55 games and hitting .226.