At the 2018 Commonwealth Games held at the Gold Coast, Australia, Proud won silver as part of the relay team with David Cumberlidge, Jarvis Parkinson and James Guy that came second in the 4x100m freestyle events. He broke his own Games record in the heats of the 50m freestyle with 21.45 seconds, then 21.30 in the semi-finals and went on to win the final in 21.35. He also won a silver in the 4x100m medley with Adam Peaty, James Guy and Luke Greenbank. He broke his own 50m freestyle British record at the Sette Colli meet in Rome, posting a Commonwealth record of 21.16 in the final to become the 4th fastest performer of all time over the distance.