A native of Dublin, Farron-Mahon relocated to Florida as a child for training and became a top-50 player on the ITF junior circuit.

[1][2] During his junior career he partnered with Marin Čilić in doubles at Wimbledon and the pair won a title together in Roehampton.

[4] Due to having a Swiss grandfather, there was purportedly some interest by Switzerland to have him switch allegiances.

[5] Farron-Mahon, who won three ITF Futures doubles titles, made a Davis Cup appearance for Ireland against Finland in Helsinki in 2006.

He partnered Kevin Sorensen for the doubles rubber, which they lost to Tuomas Ketola and Jarkko Nieminen.