It was a dominant showing from the Cubs, who are hoping to hold onto a wildcard spot and qualify for the postseason.
The scoring started early for the home team, who managed four runs at the bottom of the first from a pair of homers plus a single. Alex Bregman's two-run home run in the next inning put them up 6-0 in no time.
Chicago added three more in the fourth, keeping the NL Central-leading Brewers to six innings without scoring. By the time Cooper Pratt sent the ball over the wall at the top of the seventh, it was a mere consolation. The Cubs added another four runs from another two home runs at the bottom of the inning to go up 13-2.
Alex Bregman hit three homers for the hosts, who joined the Toronto Blue Jays, Cincinnati Reds, and New York Yankees to hit nine or more home runs in the same game. The Jays are the only one to reach 10, having done so in 1987 against the Baltimore Orioles.
Before Monday night's explosion of home runs, the last team to hit that many in a game were the Yankees last season, doing so twice.
With the impressive showing, the Cubs completed the month of August with a franchise-high 62 homers, which is also the second most by a team in MLB history behind the Yankees' 74 in the same month seven years ago.
The Brewers, currently top of the National League, are seven games ahead of the Cubs in the Central Division. Chicago, meanwhlie, currently hold the first wildcard place.
The four-game series between the two teams continues on Tuesday as the regular season concludes on September 27.