The A's said Melvin, who replaced Bob Geren June 9 when the team was suffering through a nine-game skid, has skippered the last-place squad to a 42-49 mark since then.
A native of nearby Palo Alto, Calif., Melvin has compiled a 535-557 record in eight seasons as manager for Oakland, the Seattle Mariners and Arizona Diamondbacks.
Melvin, 49, guided the Diamondbacks to the National League West title in 2007, after which he was named the NL Manager of the Year. But he was fired in May 2009 after the D-backs began the season 12-17.
Celebrity Families of 2014 [PHOTOS]