[2] League1 Ontario is a part of League1 Canada, the national third tier with regional divisions, with L1O equivalents in Alberta, British Columbia, and Quebec.

[4] Initially, six teams (ANB Futbol, Durham United FC, North Mississauga SC, ProStars FC, Sanjaxx Lions and Vaughan Azzurri) were to compete, but a seventh team (Woodbridge Strikers) was soon added ahead of the inaugural season.

[6] Durham United FC defeated North Mississauga SC by a score of 2–0 in the league's first official match.

[13] Beginning in the 2020 season, League1 Ontario and the Première ligue de soccer du Québec had planned to hold a Final Four end-of-season tournament for their women's divisions, from August 14 to 16, pitting the top two sides from each league in an inter-provincial playoff.

[17] Due to the delayed start caused by the pandemic, some clubs were unable to field team's in the main division.

[20] From this point onward, expansion clubs enter at the League2 level and have to win to earn promotion to the Championship and then Premier divisions.

[20] In September 2019, former Canadian national team player Carmelina Moscato was announced as Commissioner of the Women's division (prior to this both the male and female divisions were led by Dino Rossi),[21] however she departed in December 2020[22] to become the Director of Women's Football for the Bahamas Football Association.

[25] Beginning in 2019, the Ron Smale Cup was created by the supporters group of North Mississauga SC to be given to the regular season champions.