The singer apologised for being late on stage at London's Heaven club last night (July 26) after revealing nerves made him hide away in a toilet.
''Were a little late on tonight, because I was supposed to do a radio interview, but I got so nervous I locked myself in my own bathroom," Contactmusic quotes him as saying.
"I was going to make an inappropriate joke here, but I won't - essentially, in the end I just peed and got on with it.''
The star performed his hit single 'Big Girl (You Are Beautiful)', 'Grace Kelly' and 'Blame it on the Girls', before closing with the title track from his new album The Origin of Love.
Mika recently unveiled his new single 'Celebrate', which features Pharrell Williams.
Listen to the track in full below: