The singer was preparing for her performance at the Capital Summertime Ball at Wembley Arena when she slipped and was rushed to hospital.
Taking to Twitter, she told her fans, who she also calls her 'heartbeats', not to wait outside the venue for her.
'Just want to let my heartbeats (ones waiting outside wembley) know that I have been taken to hospital after falling of (sic) a platform,” she wrote.
“I have ripped a main ligament in my foot and have been put on crutches and told to rest. I'm in a lot pain so please dont wait in the cold for me ... sorry!'
But she vowed to take to the stage for her set. 'Dont get it twisted! I'm gonna be singing tomorrow at STB even if I have to crawl, be carried or be wheeled onto stage!” she said. “My foot is 3 times it normal size but my heartbeats rule and I will not (let) you down!'