The nickname "A's" has long been used interchangeably with "Athletics", dating to the team's early days when headline writers wanted a way to shorten the name. From 1972 through 1980, the team nickname was officially "Oakland A's", although, during that time, the Commissioner's Trophy, given out annually to the winner of baseball's World Series, still listed the team's name as the "Oakland Athletics" on the gold-plated pennant representing the Oakland franchise. According to Bill Libby's Book, Charlie O and the Angry A's, owner Charlie O. Finley banned the word "Athletics" from the club's name because he felt that name was too closely associated with former Philadelphia Athletics owner Connie Mack, and he wanted the name "Oakland A's" to become just as closely associated with him. The name also vaguely suggested the name of the old minor league Oakland Oaks, which were alternatively called the "Acorns." New owner Walter Haas restored the official name to "Athletics" in 1981, but retained the nickname "A's" for marketing purposes. At first, the word "Athletics" was restored only to the club's logo, underneath the much larger stylized-"A" that had come to represent the team since the early days. By 1987, however, the word returned, in script lettering, to the front of the team's jerseys.

The A's are the only MLB team to wear white cleats, both at home and on the road, another tradition dating back to the Finley ownership.