The 18-year-old Australian has joined the League One club until the end of the season with Bournemouth duo Adam Federici and Brad Smith the only two Aussies remaining in the Premier League.
O'Neill played five games for Burnley this season but fell further down the pecking order of coach Sean Dyche after the Clarets signed Ashley Westwood from Aston Villa.
The talented Brisbane product has shown plenty of promise for ninth placed Burnley including a solid performance in the Turf Moor side's 2-0 win against Liverpool.
Oldham manager John Sheridan hoped O'Neill would play a major role as his club fights to avoid relegation.
"He is a good young footballer and good on the ball," he said.
“Hopefully he will get hold of the ball and keep possession of it and it's a good opportunity for him to come out and play regular first team football.
"He is definitely good enough but hopefully he will come here, enjoy his time with us and help us to stay in the league."
Oldham sit in 23rd position on the League One ladder and are four points behind 20th placed Swindon Town outside the relegation zone.
O'Neill could get his first chance to play for his new club this weekend when the Latics take on 22nd placed Chesterfield.
