The band was performing at Wembley Arena yesterday, when Clifford, 19, made contact with an on-stage pyrotechnics display, suffering burns to the head.
The concert was cut short as a result of the incident, with bandmate Ashton Irwin telling the crowd, "Michael has hurt himself, so we will not be continuing the show right now. Just want to say thank you so much for coming.
"He is OK. You guys have been the best crowd we could ever ask for tonight."
"Sorry I couldn't finish the encore, but at least I look like Two-Face," he joked. He added that he is OK and thanked fans for their concern.
A representative for the band's management company did not immediately respond to a request for comment.