The Raptors made the announcement Monday. Lowry joins former Toronto star Chris Bosh as the only players in team history to be named player of the month.
Lowry averaged 22.3 points, 8.9 assists and 4.2 rebounds in 15 games, leading Toronto to an 11-4 record. He shot .463 (119-for-257) from the field and .405 (30-for-74) from three-point range.
Lowry was the lone player in the NBA to average more than 20 points and 8.5 assists in December.
This season, Lowry is averaging a career-best 20.7 points, 7.7 assists and 4.8 rebounds.
Toronto resumes league action Thursday when they host the Charlotte Hornets.
Andrew Wiggins, from Vaughan, Ont., was named the NBA's Western Conference rookie of the month, earning the distinction in November and December. He's the first Minnesota player to win the award twice a season.
Wiggins had 14 points per game and averaged 0.6 blocks, 4.1 rebounds and 0.87 steals.