The 30-year-old singer, who revealed in April that she has been battling Lyme Disease since last year, debuted her latest single, "Fly."
"Honored to have performed my song Fly at the opening ceremony for the Special Olympics tonight," Lavigne captioned an Instagram snap of her on stage singing in a studded black Alice + Olivia gown. "This was a very beautiful night for me."
It was a night long in coming.
"It 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," the singer wrote.
Lavigne added that she wrote the song to "encourage people who are facing challenges, to encourage strength and to empower."
The games, started by Eunice Kennedy Shriver, brings together thousands of intellectually disabled athletes from around the world to compete in 25 sports. Lavigne watched backstage as Shriver's daughter Maria Shriver appeared on stage during the July 25 opening ceremony.
"Inspired by the powerful words of the wonderful @mariashriver and her work to support," Lavigne wrote on Instagram.
For Lavigne the road back to health has been a difficult one.
After revealing on Twitter last December that she was "not feeling well," the singer opened up in April about her battle with Lyme Disease.
"I had no idea a bug bite could do this," Lavigne told People magazine exclusively, adding she believes she was bit by a tick last spring. "I was bedridden for five months."
Lavigne says she completely changed her diet and exercise routine, eliminating sugar, dairy and gluten and trying to walk or swim every day along with meditation and yoga. She estimates she is now about 80 percent recovered.
"I’ve never been more clear about what I want in my life: health, family, love and happiness," Lavigne said, adding she is "grateful" for "the worst thing" she’s had to face so far.