Johnson was asked by LBC-FM, London, whether he thought it was acceptable to wear shorts in the workplace amid the hot summer weather, the London Evening Standard reported Friday.
"Listen, this is a serious question. I think shorts are perfectly okay, I'm not necessarily saying I'm going to wear them myself but I see absolutely no reason why people shouldn't wear shorts if they want to," the mayor said.
Johnson said he would even be OK with Deputy Mayor Kit Malthouse wearing shorts to the office, "provided they weren't Stubbies."
Stubbies, an Australian brand, are known for fitting tightly and showing a lot of skin.
Johnson was also asked whether he goes barefoot in the office during hot weather, a practice Deputy Prime Minister Nick Clegg admitted to this week.
"I have some clogs actually, I have some very fine London Underground clogs which I wear," Johnson said.