Ryan has recently returned to Hearts from the U20 World Cup in Egypt where he starred in two matches for the Young Socceroos.
"This will be a good move for me as I need to be playing games," he said. "Hopefully being at Ayr will help my game and in turn I can help Ayr climb the table.
"I am due to come back to Hearts in January when I hope to stake a claim for first team involvement again." Ryan, who featured regularly during the Jambos' pre-season tour of Germany, made his senior debut for Hearts against Gretna on the final day of the 2007-08 campaign and also played against Barcelona at Murrayfield in July 2007.