LaVallee outpaced and outstyled Cory Davis for all three laps.
Davis posted the fastest qualifying time, but during the final LaVallee took the lead through the first corner.
"I just tried to get on the course as fast as I could and just remember to do my tricks big, and it worked out. Cory was all over me. Hats off to Cory for just charging the whole time," LaVallee said to ESPN.
LaVallee landed his tricks including the kiss-of-death flip and cordova flip. His combined score of 90.95 beat Davis' 85.66.
Davis added a silver medal to a pair of Speed & Style bronzes.
His chance at gold came after an upset over two-time Joe Parsons in the semi-finals.
Parsons and Willie Elam tangled up their handlebars during the competition for bronze. Forcing both riders off the course and wide around the first jump set.
Race officials threw a red flag and the two racers had to lineup for a restart. This produced another collision and a second red flag.
Parsons drew a penalty and was relegated to the back row for the race's third start.