 Featuring instrumentation from bass guitar, electric guitar and keyboards, "I Knew You Were Trouble"'s chorus is built around "whirring" sub-bass according to Mark Hogan from "Spin" magazine, with digitally tweaked vocal hooks and dubstep, while Jonathan Keefe of "Slant Magazine" noted that the bass drops "fit naturally into the song's slick pop-rock arrangement and make its melodic hook all the more potent.