The South American duo are joined by Tottenham's Dele Alli, Leicester's Kasper Schmeichel, Southampton's Virgil van Dijk & Sunderland's Jermain Defoe in the running for the prize
Aguero has found his best form in 2016 as City climbed to second in the table, with the Argentina international scoring five goals and providing a further assist in his four league appearances.
And Firmino has had a similarly productive month having scored twice against both Arsenal and Norwich City as well as providing an assist in his four outings.
READ MORE | Pellegrini: Aguero is irreplaceable
Jamie Vardy has already won two of the season's awards this campaign, but it is team-mate Kasper Schmeichel who gets the nod this time after keeping three clean sheets in four appearances.
The trio are joined by Southampton defender Virgil van Dijk, Sunderland striker Jermain Defoe and Tottenham midfielder Dele Alli for the monthly prize.
The winner will be announced on February 5 at 06:00 (GMT).