Sophomore center fielder Scott Cho went four for six with one RBI and four runs, while sophomore leadoff man Zach Chavez was three for four with two RBIs and four runs.
Freshman first baseman Eilert Meyers also drove in two and contributed two hits as all but one spot in the batting order produced hits for the Pirates.
OCC chased Fullerton starter Chase Yamashiro during a nine-run fourth inning in which five of the eight hits were doubles.
Yamashiro, who gave up seven runs, though only two were earned, had yielded just two earned runs in 22 2/3 innings coming in (an 0.79 earned-run average).
OCC produced at least one run against each of the first five Fullerton pitchers. Hornets' hurlers had combined to allow 21 runs in their previous six games.
The 20-run output matched a season-best for OCC, which is averaging 10.9 hits and 9.1 runs per game. The Pirates pounded Palomar, 20-4, on Feb. 23. OCC has scored in double digits five times this season.
The win not only got the Pirates off on the right foot in conference, it was an emphatic rebound from the first loss of the season, an 11-6 nonconference setback Sunday at College of the Canyons.
Fullerton (7-7, 0-1) committed six errors to suffer its most lopsided defeat of the season.
"The nice thing about us is, we put pressure on the defense," OCC Coach John Altobelli said. "[The Hornets] not playing catch today had something to do with [the win]. But we did a great job of swinging the bats and being productive and our pitchers came in and threw strikes. It was a good first conference win."
After starter Garrett Hartwell gave up two runs on three hits in 2 1/3 innings, Jed Vandernaald, Chad Thompson, Cory Davis and Josh Evans combined to post zeroes the rest of the way.