Two goals and two assists came in December as the Royals won three of their six league fixtures. The former Middlesbrough man also grabbed an assist in the 5-3 victory over non-league Harborough Town in the FA Cup.
Leyton Orient duo Omar Beckles and Tottenham Hotspur loanee Keeley were nominated as Richie Wellens' side kept six clean sheets in the month and dropped just two points, remaining unbeaten and moving up to eighth in League One.
This follows on from a superb November for 21-year-old Keeley who scored a stoppage-time equaliser for the Os' in an FA Cup win over non-league Oldham Athletic.
Reading travel to Brisbane Road on Saturday looking to be the first side to score a league goal in that corner of East London since November 26, a run of six matches.
Birmingham City pair Krystian Bielik and Jay Stansfield were also nominated alongside Huddersfield Town's David Kasumu, all crucial for both side's promotion pushes at the end of 2024.