Ryu (1-0) turned in a clutch performance for the Dodgers, who came into the contest down 2-0 in the NLCS. The Korean left-hander scattered three hits with a walk and struck out four, tossing 69-of-108 pitches for strikes in the win.
Brian Wilson hurled a scoreless eighth and Kenley Jansen posted a 1-2-3 ninth for the save as the Dodgers rebounded at home following a pair of losses in St. Louis.
Adrian Gonzalez smacked an RBI double and Yasiel Puig followed with a run-scoring triple in the fourth inning for a 2-0 lead.
Cardinals starter Adam Wainwright (0-1) yielded two runs on six hits over seven innings. He didn't issue a walk and struck out five.
Game 4 is set for Tuesday in Los Angeles.