Borna Barisic, Ryan Kent and Joe Aribo got the goals at Ibrox as Steven Gerrard's men took over from previous leaders Hibernian on goal difference.
Ross County are third following their 2-2 draw with Kilmarnock in Dingwall. Alan Power and Chris Burke scored for Killie to overturn Ross Draper's opener but Ross Stewart earned the Staggies a point with a 79th-minute penalty.
It was also 2-2 between Motherwell and Livingston at Fir Park. The Steelmen were twice ahead through David Turnbull and Alan Campbell but Lyndon Dykes (penalty) and Alan Forrest replied for Gary Holt's team.