Rowett guided his team through the hectic Christmas period with just a solitary defeat, winning 10 points from a possible 15 in the process as Albion finished 2012 in the play-off positions.
On receiving the award, Rowett told the club's official website: "It's a nice accolade to receive. I'd seen one or two of the nominations over the months so far this season and wondered if we'd have a chance.
"Actually, the month was that busy I hadn't reflected on quite how well it went. December was a good month and included the FA Cup win at Crewe.
"But the crucial thing for me is that it is for the whole group. I know it's a bit of a cliche but all of the staff have worked really hard, it's a group effort here and we've got five or six staff members who have all done more than enough to get to this point."
Rowett fended off competition from Wycombe's Gareth Ainsworth and Chris Wilder of Oxford to win the award.