Dressed in a grey jacket and black trousers and with a camera hanging around his neck, the man brandished the Mexican flag in front of Pakistan's Malala Yousafzai and India's Kailash Satyarthi as the Nobel laureates received their prize to rapturous applause.
Police led the man outside Oslo City Hall, where the ceremony was being held.
"The person has been arrested. The place is under control and police are looking into the events," the Oslo police said in a statement.
The man's motives and identity were not immediately known.