Lynn (14-10) yielded one run on four hits, overcoming four walks while striking out seven for National League Central-leading St. Louis, which reduced its magic number for winning a division crown to one.
Matt Adams smacked a two-run homer in the first inning and the Cards never trailed.
David Freese and Daniel Descalso each added two RBI for St. Louis.
Brewers starter Yovani Gallardo (11-10) was saddled with the loss despite yielding just two runs on four hits in seven innings.
Khris Davis knocked in both Milwaukee runs.
Aaron Carter is still in love with Hilary Duff
Ray Liotta sues skin care company over use of likeness