The 15-year-old pulled off one of the shocks of London 2012 when she trumped multiple Olympic and world champion Rebecca Soni to win the 100m breaststroke at the Aquatics Centre.
It wasn't the first time Meilutyte has succeeded on the Olympic stage having won the same event at the far smaller European Youth Olympic Festival in Turkey the year before.
However few would have expected what followed with Meilutyte, who attends Plymouth College, setting a new Lithuanian record in the heats at London 2012 and European record in the semi-final.
She beat American Soni by eight hundredths of a second in the final and hasn't been shy in stating her ambition to retain her title at the next Olympics in Rio in 2016.
"There is definitely a big difference between before and now," she said. "But I think about Rio every day, it's my biggest goal for the next four years.
"I had a chance to go back to Lithuania after the Olympics, before the closing ceremony, and I spent about a month there.
"I saw my family and friends that I have really missed over the years and seeing the smiles on people's faces made me really proud."
- Rebecca Soni