The former One Direction singer had been billed to hit the stage at the Capital FM Summertime Ball at London's Wembley Stadium but he disappointed gig-goers by pulling out at late notice.
As festival organisers broke the news to fans at the venue, Malik took to social media to try and explain himself in a lengthy note.
"I flew into the UK last night to appear in my home country in front of my family, friends and most importantly, my UK fans," he wrote.
Malik went on to apologise for letting his fans down after they had patiently waited to see him perform, but promised to make it up to them as soon as he could.
"I know those who suffer anxiety will understand and I hope those who don't can empathize with my situation," he added.