Jordan Adams hit a tie-breaking 3-pointer with 45 seconds remaining to propel UCLA to victory.
Watson allows just one run in eight innings to lead Bruins to series-clinching win.
Marcus Nilsson earns All-American honors in the heptathlon
Ally Carda struck out five in a two-hit shutout and Brittany Moeai drove in the game's lone run.
Annika Lenz placed fourth, while Montana Monahan had a personal best on the last day of NCAA Zones.