Waterhouse secured the sixth final play-off spot with a 1-0 win against Harbour View in the Wray and Nephew/Jamaica Premier League, at the Drewsland stadium, on Sunday.
The Marcel Gayle coached side needed to win and it took a second half goal to secure all three points.
The victory for Waterhouse means seventh place Montego Bay United fail in their bid to reach the play-offs despite a 2-1 win against Tivoli Gardens.
Montego Bay has only suffered one defeat in 2024 and Sunday’s victory was their fifth straight.
Meanwhile, Cavalier benefitted from Tivoli’s defeat and moved into second place following their 6-0 whipping of Molynes United.
Champions Mount Pleasant maintained top spot after beating Lime Hall Academy 2-1.
In other results, Dunbeholden beat Vere United 4-2, Portmore United beat 10-man Humble Lion 2-0 and Arnett Gardens defeated 10-man Treasure Beach 4-1.