Payette was born on October 20, 1963, in Montreal, Quebec, and lived in the Ahuntsic neighbourhood, attending Collège Mont-Saint-Louis and Collège Regina Assumpta. In 1982 she completed an International Baccalaureate diploma at the United World College of the Atlantic in South Wales, United Kingdom.

For her undergraduate studies, Payette enrolled in McGill University where she completed a Bachelor of Engineering degree in electrical engineering in 1986, after which she completed a Master of Applied Science degree in computer engineering at the University of Toronto in 1990. Her thesis focused on computational linguistics, a field of artificial intelligence. She is a retired member of the Ordre des ingénieurs du Québec.

During her schooling, between 1986 and 1988, Payette also worked as a systems engineer for IBM Canada’s Science Engineering division. From 1988 to 1990, as a graduate student at the University of Toronto, she was involved in a high-performance computer architecture project and worked as a teaching assistant. At the beginning of 1991, Payette joined the communications and science department of the IBM Zurich Research Laboratory in Switzerland, for a one-year visiting scientist appointment. When she returned to Canada, in January 1992, she joined the Speech Research Group of Bell-Northern Research in Montreal where she was responsible for a project in telephone speech comprehension using computer voice recognition.

Payette was selected by the Canadian Space Agency (CSA) as one of four astronauts from a field of 5,330 applicants in June 1992. After undergoing basic training in Canada, she worked as a technical advisor for the Mobile Servicing System, an advanced robotics system and Canada’s contribution to the International Space Station. In 1993, Payette established the Human-Computer Interaction Group at the Canadian Astronaut Program and served as a technical specialist on the NATO International Research Study Group on speech processing.

In preparation for a space assignment, Payette obtained her commercial pilot licence and logged 120 hours as a research operator on reduced gravity aircraft. In April 1996, Payette was certified as a one-atmosphere deep sea diving suit operator. Payette obtained her captaincy on the CT-114 Tutor military jet at CFB Moose Jaw in February 1996 and her military instrument rating in 1997. Payette has logged more than 1,300 hours of flight time, including 600 hours on high-performance jet aircraft.

Payette reported to the Johnson Space Center in August 1996 to begin mission specialist training. After completing one year of training, she was assigned to work on the Mobile Servicing System. Payette completed the initial astronaut training in April 1998.

Payette was married twice, first to François Brissette in the 1990s, and secondly to William Flynn, with whom she had a son in 2003, and from whom she divorced in 2015. She is fluent in French (her mother tongue) and English, and can converse in Spanish, German, Italian and Russian. Payette plays the piano and has sung with the Montreal Symphony Orchestra, Tafelmusik Chamber Choir. Currently, she sings with the Ottawa Bach Choir. Among her other hobbies are running, skiing, racquet sports, and scuba diving.

Payette visited the space station again in 2009 as a mission specialist aboard Space Shuttle Endeavour during mission STS-127 from July 15 to 31, 2009, and was the flight engineer and lead robotic operator during the mission. At that time, Robert Thirsk was a member of Expedition 20 on the space station. Endeavour’s docking at the space station marked the first time two Canadians met in space.

Payette was charged with second degree assault in Maryland, on November 24, 2011. At least one anonymously quoted source has alleged that the victim of the assault was her then-husband, Billie Flynn. Though the charges were later dropped, the couple split several weeks later and subsequently divorced. Payette has stated that charges were “unfounded” but refused to comment further on the circumstances leading to her being charged with assault.

Payette has served on boards of directors, at Queen’s University, Canada’s Own the Podium Olympic program, Montreal Science Centre foundation, Robotique FIRST Québec, Drug Free Kids Canada, the Montreal Bach Festival, the National Bank of Canada, Développement Aéroport Saint-Hubert de Longueuil, and others. In about 2017, she was appointed to the International Olympic Committee’s Women in Sports Commission. She is a member of the Ordre des ingénieurs du Québec and a fellow of the International Academy of Astronautics. As well, Payette is a member of the Faculty of Engineering Advisory Board of McGill University.

Payette was announced on July 13, 2017, as Prime Minister Justin Trudeau’s recommendation to be the 29th Governor General of Canada. She was scheduled to take office October 2, 2017, after the completion of briefings from the incumbent, David Johnston. After the announcement was made, Johnston issued a statement congratulating Payette and welcoming “a Canadian of extraordinary achievement, admired by all”.

As governor general-designate, Payette had her first official meeting with Queen Elizabeth II on September 20, 2017, at Balmoral Castle, when she was also invested by Her Majesty as an extraordinary Companion of the Order of Canada (CC), an extraordinary Commander of the Order of Military Merit (CMM), and a Commander of the Order of Merit of the Police Forces (COM).

Payette was installed as governor general on October 2, 2017. Afterwards, she urged Canadians to work together on issues such as climate change, migration and poverty. “Anyone can accomplish anything and rise to the challenge as long as they are willing to work with others, to let go of the personal agenda, to reach a higher goal and to do what is right for the common good. This is exactly what I hope my mandate as the governor-general will reflect”, Payette said.

As she was completing her first year as the viceregal representative in September 2018, Payette faced some criticism about controversial comments she had made against those who believe in creationism and those who did not believe in climate change. At the Canadian Science Policy Conference the next month, she argued strongly for greater public acceptance of science, saying that too many people believe in astrology, deny climate change, and believe that “maybe taking a sugar pill will cure cancer”. Committee for Skeptical Inquiry concerning climate change, commented that her remarks were “refreshing”. George Dvorsky from Gizmodo.org stated “Her words were a breath of fresh air”.

On July 21, 2020, CBC News reported that Payette had allegedly created a toxic work environment at Rideau Hall by verbally abusing employees. Two days later, spurred on by the CBC News report, the Privy Council Office formally launched an investigation into her conduct. Multiple former employees of the Montreal Science Center told the National Post they witnessed similarly abusive behaviour by Payette in her time at the institution, although others described her behaviour as the result of rigorously high standards.