Avril Lavigne looked radiant as she took to the stage at the opening ceremony of the 2015 Special Olympics World Games.

The 30-year-old singer revealed earlier this year she has been diagnosed with Lyme disease, a bacterial infection that if left untreated causes severe joint pain and extreme tiredness.

Avril looked beautiful in a floor-length, sleeveless black sparkling gown as she performed her song Fly in front of the crowd at the Los Angeles Memorial Coliseum.

Avril Lavigne performs at the Opening Ceremony of the 2015 Special Olympics World Games at Los Angeles Memorial Coliseum
Avril Lavigne performed her song Fly at the Special Olympics World Games opening ceremony (Rich Fury/Invision)

She later wrote on Instagram: β€œThis was a very beautiful night for me.

β€œIt has been a difficult year fighting through Lyme Disease for me and I am so happy to have made it on stage tonight for the first performance in a year. Thank you for having me and please enjoy my song Fly. I wrote this song to encourage people who are facing challenges, to encourage strength and to empower.”

She also shared a picture of herself backstage, waiting to perform.

Avril – who is married to Nickelback frontman Chad Kroeger – first spoke out in December 2014 on social media to deny rumours she was in rehab and explain she was undergoing serious health problems.

In June she gave an emotional interview, explaining doctors had struggled to diagnose her condition, but she is now halfway through her treatment and on the mend.