- In December 1986, former Quebecair employees and managers founded Air Transat as an off-shoot of Trafic Voyages.
- Air Transat’s first flight took place on the 14th of November, 1987, connecting Montreal to Acapulco.
- In 1993, Air Transat took over Nationair’s aircraft and maintenance base.
- In 2008, Air Transat became a member of the International Air Transport Association (IATA).
- In 2009, Transat A.T. announced a five-year partnership with CanJet, replacing an agreement with Westjet.
- In 2011, Air Transat won the Family Friendly Airline Award. Created by the Kids First Fund, this international distinction, awarded to air carriers that provide additional services and extra comfort to children and their parents, was awarded to Air Transat for a second time in 2012.
- In 2012, Air Transat was named World’s Best Leisure Airline at the Skytrax annual World Airline Awards.
- In September 2013, Air Transat struck a seasonal lease deal with Air France-KLM leisure carrier Transavia France, covering the lease of up to nine B737-800s by 2019.
In September 2014, Air Transat introduced the new Eco Fares, offering more flexibility in Economy Class. With the new Eco Fares that offer varying conditions for flight changes or cancellation, passengers will be able to choose the level of flexibility that suits them best so that they can modify travel dates or even cancel the trip if necessary.
As of May 2016, Air Transat offers Club Class service on domestic flights. On Boeing 737 aircraft, Club Class seats will be located in the first three rows of the Economy cabin, with the middle seats in each of these rows remaining unoccupied.
In July 2016, at the Skytrax World Airline Awards, Air Transat has been voted for the fifth consecutive year Best North American Leisure Airline.
As of November 2016, Air Transat applies its new checked baggage allowance policy, which increased all free baggage allowances. Aiming to simplify and standardize the baggage policy, the number of pieces of checked baggage is taken into consideration in addition to the weight. Also, Air Transat aligned itself with other Canadian carriers by applying a $25 CAD fee on the first piece of checked baggage, per flight segment, for Economy Class passengers who have booked flights only (except flights to/from Europe).
In November 2016, for the sixth year in a row, Air Transat has been ranked the most climate-friendly airline in North America in the Atmosfair Airline Index, which measures carriers’ fuel efficiency and greenhouse gas emissions reduction and helps travelers choose their airlines based on CO2 emission levels. Air Transat ranked 12th in the world in the long-haul and medium-haul categories, and 14th in all categories of the Atmosfair Airline Index, published by the German NGO Atmosfair, thus remaining one of the world’s leading environmentally friendly airlines.
- In 2018 and 2019, two years in a row, Air Transat was named World’s Best Leisure Airline by Skytrax.
- In May-June 2019, the parent company of Air Transat, Transat AT, held exclusive talks of purchase with Air Canada that made an all-cash bid offer of C$520 million. The Board of Transat AT accepted Air Canada’s bid, but the deal requires approval by two-thirds of shareholders and regulatory and governmental approval. Air Transat will continue to operate as a separate brand if the sale of Transat AT to Air Canada is concluded.
- Air Transat is now Canada’s leading holiday travel airline, carrying almost 5 million passengers annually and employing almost 5,000 people.
- No fatal incidents involving Air Transat aircraft have been recorded so far.