The pop sensation met Stephen Harper on Friday to be presented with the Diamond Jubilee Medal - an honour which marks significant achievements by Canadians - but he faced a backlash after wearing dungarees to the ceremony, with some people posting messages online slating his choice of outfit and one website even labelling him a "white trash prince".
But the star has now hit back at the criticism, explaining that he attended the ceremony straight after another event and didn't have anything to change into.
He wrote on his Instagram page: "The pic of me and the prime minister was taken in a room in the arena where i was performing at that day. I walked straight from my meet and greet to him."
The 18-year-old continued that it would be "crazy" to expect him to have a change of clothes, particularly a suit, on him at the time.
"It wasn't like it was like I was going into his environment, we were at a hockey arena," he said.
Harper also weighed in on Twitter, writing: "In fairness to (Bieber) I told him I would be wearing my overalls too."
Two days after the event, Justin faced a hostile homecoming during his half-time performance at Canada's football Grey Cup, facing boos and jeers.
The Toronto crowd booed when star's face popped up on the JumboTron screen, and again when a host spoke his name. They also booed as he took the stage and throughout his performance.
However, if the teen was bothered, it didn't show. "Thank you so much Canada," he said. "I love you."