As the prime minister addressed a world forum on the French language, the man walked to the front of the large room and delivered a message of his own.
"Stop Harper, stop Jean Charest," the protester yelled in his outburst.
"Citizens rise up. We need you, everybody."
The interruption lasted only a few seconds before the man was grabbed by two security guards and hustled out of the room through a side door.
His rant earned him a muffled applause from some of the attendees inside the Quebec City conference centre.
Quebec provincial police later indicated that the man, in his 30s, was released and will not face charges.
The disruption happened just seconds after Harper uttered the only English words of his mostly French address during the conference's opening ceremony.
"As Canadians, we are extremely proud of our two national languages and our heritage of diversity," Harper said, a moment before the protester raised his voice.
The man's shouts interrupted Harper's next sentence, forcing the prime minister to pause and then repeat the line, which referred to the Olympic Games.
"Our two languages unite us, like they will unite all of humanity in a few a weeks in London, where La Francophonie will have as a great witness, a great Canadian, (former governor general) Michaelle Jean," Harper said after the brief pause, during which the protester was removed from the room.
In his speech, Harper also noted the importance of French culture in Canada. He told the room that French is the mother tongue of seven million Canadians.
Around 1,500 delegates, mostly youths, from 100 countries around the globe are taking part in the multi-day conference, which focuses on issues such as the future of the French language in the world. This is the inaugural edition of the forum.
A group of protesters that gathered outside the conference centre during the event criticized the federal and provincial governments for not doing enough to protect the French language.
An organization that promotes the preservation of the French language wrote a letter to La Francophonie secretary general Abdou Diouf, who also participated in Monday's opening ceremony.
Mario Beaulieu, president of Mouvement Quebec francais, wrote in the letter that the French language is "stagnating" and "declining." He added that the situation is far from what the federal and provincial governments lead people to believe.
Inside the building, Charest expressed his own concerns for the fate of the language, but cited international examples.
"At the United Nations, (French) influence is no longer the same," said the Quebec premier, who took the podium after Harper. "In Europe, the world of media and advertising has mostly made English its main language."
By contrast, Charest described Quebec as a model of hope for the survival of French in the world.
"The history of Quebec provides a foundation for this belief," he said.
Also on HuffPost