Simpson looked in danger of missing a spot on the second lap in his semi-final but he managed to snare third with a time of 52.16 seconds.
Ahead of the Commonwealth Games, Simpson declared his main objective was to make it in the final.
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“Pretty wild, pretty special. That was my goal to make sure I got into the final – just relieved that I am,” he said.
“I will probably go back and watch it right away and make sure there are things I can find [to improve].”
The singer has a personal best of 51.79 in the 100m butterfly, achieved in the heats at the Australian trials in May.
That time would have seen Simpson qualify in third place for the final in Birmingham.
It continues a remarkable story for the pop star turned swimmer who finished last in the final for the event at the Australian trials a year ago.
His Australian teammate, Temple, is the favourite to take out the final, which will be his maiden individual Commonwealth Games medal.
Simpson’s performance capped off another big night in the pool for Australia with Kyle Chalmers, Kaylee McKeown, Emma McKeon and Matt Levy all winning gold medals.
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