Singer/actress Miley Cyrus overcame a bout of ill health to perform at a birthday event for Muhammad Ali on Saturday night.

The former Hannah Montana star signed up for Celebrity Fight Night in Arizona, which also doubled as a 70th birthday celebration for the legendary boxer.

Her performance was left in doubt earlier this week when she revealed she was battling sickness, but Cyrus fought off her illness to attend the bash with her boyfriend Liam Hemsworth.

In a post on her page on Saturday, she wrote, "Stoked for @CelebFightNight :) awesome to have (singer) @JohnzoWest and Liam at my table here tonight."

Lionel Richie, Rascal Flatts and Tom Hanks' wife, actress-turned-singer Rita Wilson, also hit the stage at the bash, which was to raise funds for the Muhammad Ali Parkinson Center at the St Joseph's hospital in Phoenix.

Ali, who turned 70 in January, was diagnosed with Parkinson's disease in 1984.