Robertson tied the mark set by James Buckner of Lewiston in the seventh inning with a single to left field. He smacked his 21st double of the year, again to left, to take the record outright.
"It's special," Robertson said. "I didn't really get it when everyone was cheering, but then later I realized what it is. I thought about how many players have been through the Northwest League over all those years."
Coaches started making him aware of the record when he reached the mid-90s in hits.
"I really didn't think anything of it, because we were in a playoff race," Robertson said. "And then the hits just kept piling up.
"You just don't put pressure on yourself," he added. "The moment is pressure enough. I just thought about the 113 I got without the pressure."
That was of some consolation to Robertson, whose Emeralds bested the AquaSox, 4-3, in 10 innings but were eliminated from the postseason when the defending-champion Salem-Keizer Volcanoes blanked the Vancouver Canadians, 3-0.
Robertson also leads the pack with a .380 average and 59 runs, is second in RBIs (45) behind Salem-Keizer's Mike Loberg and stands third in steals (20). His record-breaking two-bagger moved him into a tie with Boise's Andrew Rundle for doubles, four off the pace set by the Hawks' Josh Vitters.
The 5-foot-9 outfielder was selected by the San Diego Padres in the 33rd round of June's First-Year Player Draft. He played one season at Oregon State after spending three years at Concordia College.
Robertson went 4-for-5 on the night, also singling to center in the third and grounding an infield hit to third base to lead off the fifth. It marked the 11th time this year that he collected three or more hits in a game.
After setting the record, Robertson was thrown out at home on an ensuing play in the bottom of the ninth. But Eugene (39-36) won the game when Cole Figueroa crossed the plate on a wild pitch by Matthew Renfree (0-2) in the 10th.
Tyler Davis picked up the win after allowing a hit and striking out one in one inning. Davis relieved Rob Musgrave who fanned five in two frames.
Welington Dotel scored twice and Jharmidy De Jesus had two hits and drove in a run for Everett (32-43).
Paige Schector is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.