Crystal Palace fans voted for Cahill to win the award, with the centre-back receiving 51% of votes.
The former England captain joined Palace in the summer and has played six times for the south Londoners, including three full matches in September.
Upon receiving the ManBetX Player of the Month trophy, Cahill said: "Thank you! I’ve just come to the club so I’m delighted to have got this.
“I want to thank the fans and also I want to thank my teammates and the staff around the Training Ground that have helped me settle in so fast. I appreciate that, I’ve enjoyed it and there’s plenty more hard work to come.”
Reflecting on the team’s performance across September, which saw a loss, draw and win respectively, Cahill said: “The Spurs game was a bit of a slap across our face I think. We were knocked off in that game and it’s unlike us from what I’ve seen from when I first came.
“We quickly rectified that and got back to the kind of performances that we expect. This month has been okay for us and we’ve put ourselves in a position at the start of this season and, like I said, there’s plenty more to come with a tough month next month.”
You can listen to full commentary of how Cahill and his Palace teammates fare this weekend by grabbing a Palace Audio pass for the Eagles’ clash with West Ham!