 Junior B | |
| Sport | Box lacrosse |
|---|---|
| Founded | 1965 |
| Commissioner | Dave Vernon |
| No. of teams | 24 |
| Country |  Canada |
| Most recent champion(s) | Akwesasne Thunder (2023) |
The Ontario Junior B Lacrosse League (OJBLL) is a box lacrosse league sanctioned by the Ontario Lacrosse Association in Canada. The league features twenty-five teams in Ontario, one in Quebec, and one in the Akwesasne (which straddles the two aforementioned provinces and New York) that annually play a 20-game schedule and four rounds of playoffs for the J. A. MacDonald Trophy. After the conclusion of the playoffs, a league champion represents the OJBLL at the Founders Cup National Junior B Championship.