The 22-year-old scored five goals and registered two assists in a month which saw the Tykes string together a five-game unbeaten run, including a point against promotion favourites West Bromwich Albion.
"I am really happy to win the award. The overall goal is that the team needs to win matches, but it is always nice to get recognition as part of that," said Chaplin.
"If you win an award like this, I think it shows that you are doing your best for the team, but there is always room for improvement and I would sacrifice any award for myself if it meant the team winning more matches.
"We've got a big game this weekend and I hope we can continue our recent good form."
Struber added: "I am very happy for Conor. He has been a very important player for us and his goals have helped us a lot. He has a great mentality and wants to learn quickly. You can see how well he is doing and that he deserves this award, his goals have been very important, he needs to continue this now and I think he can do that."
Despite an impressive December, Barnsley still remain firmly in the relegation mix and currently sit 23rd in the table, three points from safety.