Alishawuan Taylor scored 16 points to lead five Titans in double figures in a season-opening win.
Tyler Combs and Brad Lackey each added 13 points, Ethan Smith scored 12 and Zack Reznick had 11 for Union.
The host Titans took control by outscoring Mountain View 17-4 in the third quarter.
“It was a typical first game, but we did some good things,” Union coach Blake Conley said.
Alex Bailey scored 25 points to lead Mountain View (1-1).
UNION 77, MOUNTAIN VIEW 59
MOUNTAIN VIEW (1-1) — Michael Bolds 2, Makai Anderson 9, Philip Earnhardt 10, Alex Hegel 2, Trevor Green 6, Sam Frosch 0, Will Prescott 2, Alex Bailey 25, Rodolfo Montiel 3. Totals 19 (9) 12-16 59.