The Hatters won all five of their games last month, with the 1-0 win over Northampton enough to guide the Town to top spot.
Striker Cullen was a major contributor to the Town’s success, notching five goals in a three-match spell in October, including a first-ever senior hat-trick in the 3-1 win over Dagenham & Redbridge on 21st October.
The boss faces competition from Newport’s Justin Edinburgh, Shrewsbury chief Micky Mellon and Plymouth manager John Sheridan.
Cullen is up against Cambridge striker Kwesi Appiah, Plymouth centre-half Carl McHugh and Carlisle midfielder Brad Potts.
Town defender Luke Wilkinson scooped the player of the month gong last month.
The winners will be announced on Friday.