McCutchen put the Brewers ahead to stay when he drove in Rowdy Tellez with a fielder's choice in the fifth inning. The five-time All-Star made it 5-2 with a two-run double in the seventh, running his total to 1,002 RBIs.
"I've been doing it for a while, I guess,'' said McCutchen, a 14-year veteran who won the 2013 NL MVP award with Pittsburgh. "Anybody who can have that attached to them means you've been doing it for a while and doing it right.''
"Longevity,'' manager Craig Counsell said. "It's being good for a long time. It means 100 RBIs a year for 10 years. That's wild. It means playing a lot of games and staying healthy and then doing a lot of damage.''
Milwaukee (81-70) earned its third consecutive win. Heading into the day, the Brewers trailed Philadelphia by 2 1/2 games for the third NL wild card.
The Associated Press contributed to this report.