Ethan Smith hit seven 3-pointers and finished with 25 points and Tyler Combs also scored 25 for Union.
Union hit 15 3-pointers as a team.
The Titans clinched a share of the 4A Greater St. Helens League title. Union will face Skyview at 7 p.m. Friday at Evergreen for the district title and the No. 1 seed to the bi-district tournament.
Battle Ground will face Camas at 5 p.m. Friday at Evergreen for the third and final bi-district berth from the 4A GSHL.
UNION 99, BATTLE GROUND 58
BATTLE GROUND — Vincent McCormic 8, KeAndre Hunter Holliday 10, Brendan Beall 14, Colin Barton 5, Kaden Perry, 9 Elijah Parker 9, Scott Hatch 3. Totals 21 (7) 9-16 58.