The men's division grew slightly to 17 teams for this season, with the addition of Darby FC, Unionville Milliken SC, and Alliance United FC. Durham United FA and North Toronto Nitros did not return for this season. During the off-season, Jim Brennan stepped down as head of Aurora FC to accept a position with York 9 FC in the Canadian Premier League. FC London also announced the affiliation of its youth academy with professional side Toronto FC. This season saw expanded playoffs and a return to single-table competition for the men's division. The top eight teams overall from the men's division entered the playoffs, which consisted of a group stage and a final championship match between the winner of each group. The women's side saw a shorter season which ended in August, followed by a four-team elimination playoff for the league title.
Teams
Regular season
Each team played 16 matches as part of the season; one match against all other teams. The top eight teams competed in the league playoffs at the end of the season, the winner of which earned entry into the 2019 Canadian Championship.
Playoffs
The top eight teams from the regular season were divided into two groups of four for the playoffs. Each team played three matches; one match against all other teams in their group. The top team from each group advanced to the league championship, the winner of which earned entry into the 2019 Canadian Championship.
Group stage
;Group A ;Group B
League Championship
The league champion was determined by a single match between the two group winners in the first round of the playoffs. The winner qualified for the 2019 Canadian Championship.
Cup
The cup tournament is a separate contest from the rest of the season, in which all 17 teams from the men's division took part. It is not a form of playoffs at the end of the season, but is more like the Canadian Championship or the FA Cup, albeit only for League1 Ontario teams. All matches are separate from the regular season, and are not reflected in the season standings. The cup tournament for the men's division is a single-match knockout tournament with a total of four rounds culminating in a final match in the start of August, with initial matches determined by random draw. Each match in the tournament must return a result; any match drawn after 90 minutes advanced directly to kicks from the penalty mark instead of extra time.
Preliminary Round
First Round
Quarterfinals
Semifinals
Final
Statistics
Top goalscorers
Updated to matches played on August 18, 2018. Source: