Kia, a Vocal Performance student at the University of Wales Trinity St David, said the musical director from the college was contacted by a lady from the event - and he chose the first years of the University's Cardiff campus to become the Academy Voices.
"We found out just before we all came home for the Easter holidays and started to rehearse as soon as we got back," said Kia.
"I was honestly so shocked.
"I couldn’t believe that we’d been chosen to represent Wales for the performance.
"My whole class was absolutely speechless."
She said from Wednesday to Saturday last week, the choir had the pleasure of singing with a Rebecca Devereux, a singer and songwriter; they performed Sing by Andrew Lloyd Webber and Gary Barlow and also performed Calon Lân, a Welsh song, and Rule Britannia with her.
On each occasion, they sang to a member of the Royal family including Princess Beatrice and the Earl and Countess of Wessex.
And then on Sunday, when the performance was televised, Kia and her fellow choir members sang Calon Lân and Rule Britannia with Katherine Jenkins.
As the Queen was driven around the arena, they also sang Beacon of Brightest Light, which was written by Debbie Wiseman especially for the Platinum Jubilee.
Understandably, Kia said she was nervous, adding: "I’ve never experienced anything like it.
"I think it was even more nerve wracking knowing that the Queen was there watching us all perform."
And the reaction from her family?
"I think my mum was probably crying but every single member of my family said they are so proud of me," added Kia.