Melvin beat out Baltimore's Buck Showalter for the AL honor in a close vote by the Baseball Writers' Association of America. Under Melvin, the A's made a 20-game improvement, finishing 94-68 and winning the AL West.
Johnson was an easy choice for the NL prize after the Nationals -- who never had enjoyed a winning year -- had the best record in the majors and their first playoff appearance.
Johnson, who turns 70 in January, was honored for the second time. He was tabbed as the AL's top manager in 1997, hours after he resigned from the Orioles in a feud with owner Peter Angelos.
Melvin also became a two-time winner, having been chosen in 2007 with Arizona. -- AP