Baltimore, which lost 93 games in 2011, broke its streak of 14 consecutive losing seasons by winning 93 games and the AL Wild Card this past season.
"It's quite an honor coming from my peers, but I view this as a team award. I really do," Showalter said in a statement. "The players, coaches and everyone involved made this possible.
"We had some injuries along the way, we had some bumps in the road, but everyone does over 162 games. We never turned it into a woe-is-me situation. We played through it."
The award was voted upon by AL managers. Showalter received four votes, Oakland's Bob Melvin had three and White Sox manager Robin Ventura received one.