[10] Two months later at the final leg of the 2012 World Cup in Singapore, Horton won the 1500 metre freestyle event in 14:54.25.

The team of Horton, Leong, Isaac Jones and Jack McLoughlin finished second behind the British in the 4 × 200 m freestyle relay event.

[28] "It feels like all my hard work has paid off and being able to back up with two big competitions this year has given me more confidence for the future and I'm really excited to see how far I can go."

At the 2019 World Aquatics Championships, Horton won silver in the 400 m freestyle event where he came runner up to Sun Yang.

"[39] Horton has been criticised for remaining silent on Australian swimmers who have faced punishments for violating anti-doping rules.

[40] At the 2021 Australian Swimming Trials, Horton came third in the qualification final for the 400m freestyle, failing to qualify behind Elijah Winnington and Jack McLoughlin.

[41] At the 2021 Australian Swimming Trials, Horton came third in the qualification final for the 400m freestyle, failing to qualify behind Elijah Winnington and Jack McLoughlin.

[46] Day three of the 2022 World Short Course Championships, contested at Melbourne Sports and Aquatic Centre, he ranked fourth in the preliminaries of the 400 metre freestyle with a time of 3:38.09 and qualified for the evening final.

[49][50] In the inaugural men's 800 metre freestyle at a World Short Course Championships, the following day, he placed ninth overall with a time of 7:40.64.