Southam won the men's 100m freestyle swimming final at the Glasgow 2026 Commonwealth Games on July 28 setting a new games record. He held the previous record of 47.09 set on day one of the games.

The world record of 46.40 in the event is held by China's Zhanle Pan and was set at the Paris Olympics in 2024. Flynn also won gold in the men’s 4x100m freestyle relay team. Henry Allan, Sam Williamson, Matthew Temple and Flynn Southam combined to set another Games record 3:28.71.

On the 100m freestyle record and win Southam said: "Me and Kyle have utmost respect for one another. But it's my time to shine, and I know that. I've been due for this, and this is my breakout meet. Four years ago, I came here as a little boy — but now I'm a man, and I belong here."

At the 2022 Junior Pan Pacific Championships, Southam won gold medals in the 50 metre freestyle, 100 metre freestyle, and 200 metre freestyle.