The 21-year-old Commonwealth Games 50 metres butterfly and freestyle champion will be an outside medal contender in the 50m free and arrives in Brazil with the sixth fastest time of the year.
Should the stars align, "Proud Brit" headlines will follow but Malaysia – a country that to date has only ever won medals in badminton and diving – can take some credit for his formative years.
In 2011, aged 16 and swimming in the Malaysian Open, Proud set a national record in 50m butterfly and was presented with a career-defining choice.
"Coming off the medal podium I was approached by someone who said 'Look, if you want to we can offer you dual nationality to swim for Malaysia.' Being quite patriotic to Malaysia as well as England, it was tempting," he said.
"But I couldn't give away my shot of swimming for Great Britain at such a young age. I'm really glad I didn't make that decision too early because the support I've been given ever since...has been a massive game changer."
Although older brother Oliver did represent Malaysia internationally in wakeboarding, being the godson of British Olympic Association (BOA) chief executive Bill Sweeney may have helped sway the younger sibling's decision.
At the European championships in London in May, Proud won 50m freestyle bronze behind Olympic champion Florent Manaudou of France whose big rivals in Rio will be Australian Cameron McEvoy and American Nathan Adrian.
