September provided lots of match time to rate player performances with four Magners League clashes.
Leinster's three wins during September against Dragons, Ospreys and Edinburgh helped to put the province in their current position, top of the league table.
Flanker McLaughlin played in all four games and took the opportunity to impress Leinster's followers with energetic performances, making him supporters top choice in September.
An appreciative McLaughlin said: "I am delighted to receive this award, it is a great honour to be recognised by the Leinster supporters.
"I've worked hard over the past few months and look forward to continuing this for the supporters and for the team."
With the next Heineken Cup encounter just days away, he added: "We're really looking forward to the game against Brive, it is a chance to get back on track following last week's defeat to London Irish."