Hansen, 47, will be joined by three US astronauts for a historic crewed mission to the moon that will be the first since the end of the Apollo programme 50 years ago.
Canadian Prime Minister Justin Trudeau, speaking to reporters in Quebec, said he was extraordinarily excited for Hansen.
“I’ve known him for a number of years and he is an exceptional individual and will do all Canadians proud,” Trudeau said. “It’s a great day for Canada.”
The mission, Artemis II, will also include the first woman, Christina Koch, and the first African American, Victor Glover, ever assigned as astronauts to a lunar mission.
Hansen was born in the city of London in Canada’s most populous province of Ontario and his aviation journey started at the age of 12 when he joined the Royal Canadian Air Cadet Squadron.
He served as a fighter pilot with the Royal Canadian Air Force between 2004 and 2009, before being picked for an astronaut recruitment program by the Canadian Space Agency.
“All of our leadership … all of those have added up to this moment where a Canadian is going to the moon with our international partnership and it is glorious,” Hansen said after his selection.
Canada has had a few astronauts who have flown into space, including retired astronaut Chris Hadfield – the first Canadian to perform a spacewalk – but none has travelled beyond Earth’s orbit.
The crew members were announced by Nasa and the Canadian Space Agency at an event near Nasa’s Johnson Space Center in Houston.
The Artemis II mission will mark the debut crewed flight – but not the first lunar landing – of an Apollo successor programme aimed at returning astronauts to the moon’s surface this decade.
The kickoff Artemis I mission was successfully completed in December 2022, capping the inaugural launch of Nasa’s powerful next-generation mega-rocket and its newly built Orion spacecraft on an uncrewed test flight that lasted 25 days.
(Reporting by Ismail Shakil; Editing by Sandra Maler.)