The booster used to launch RADARSAT had previously seen service in Florida, sending the Crew Dragon demonstrator to the International Space Station before landing on a drone ship stationed in the Atlantic ocean.
The Falcon 9 rocket lifted off at 7.17am local time (3.17pm Irish time). The three satellites will orbit Earth at an altitude of 370 miles.
The Falcon 9 launched at 14:17 UTC, the first stage burning for just over two minutes before separating from the second stage and performing a boostback burn to head back to Landing Zone 4 (LZ-4). Two Radarsat satellites have made it to Earth orbit to date.
The RADARSAT Constellation is the third RADARSAT mission Canada has launched.
The constellation of three satellites will provide daily images of Canada's territory and maritime approaches, as well as images of the Arctic, up to four times a day, according to the Canadian Space Agency.
The images are used for a range of purposes, including tracking of sea ice, vessels, surface winds and oil pollution, as well as disaster management - especially the recurring problem of flooding - and monitoring of agriculture, forestry and land changes. Radarsat-2 was launched in 2007 and is still operational, but the new three-satellite constellation is created to greatly increase coverage, according to the space agency. RADARSAT-1, launched in 1995 from Vandenberg on a Delta II, finally died in 2013 after exceeding its design life by over 12 years.