Bryant, 23, had gone 20 games and 73 at-bats before taking Brewers starter Kyle Lohse's first pitch, a slider, out of Miller Park with two runners on. It was the Cubs' first three-run home run this season.
"Get the first one out of the way. Kind of been a while, but I did it," Bryant said after the game. "It was a cool feeling, but it would be nice to get a win out of it. It will still be a day I'll remember."
As Bryant rounded the bases, the entire Cubs team ran into the clubhouse so when he arrived back it was empty.
"It's pretty funny that they all came in here [the clubhouse] and when I come back to the dugout nobody was in the dugout, so that was pretty funny," Bryant said. "We had a good time with it. They were waiting by the door. It was kind of like a mosh pit, punching me and all that kind of stuff."
Added Cubs manager Joe Maddon of the prank: "It's a perfect ballpark for it. The dugout is so close to the clubhouse."
The 20 games without a home run was the longest streak in Bryant's collegiate or professional career.
His power outage notwithstanding, Bryant made it clear his approach and mindset at the plate had not changed.
"I went up to the plate with confidence, and it paid off for me," he said.
Bryant was the second overall pick in the 2013 draft before leading the minor leagues in home runs last season with 43.
He finished 1-for-4 with three RBIs on Saturday to bring his total to 17 since being called up to the majors.
Bryant gets the silent treatment
After Cubs OF Kris Bryant knocks his first major league HR out of the park, he gets the rookie treatment by his teammates when he returns to the dugout.