Marshall finished with nine grabs while Charles Tillman led Chicago's stifling defense with nine tackles and forced four fumbles as the NFC Central-leading Bears (7-1) reeled off their seventh straight win.
Jay Cutler completed 19-for-26 passes for 229 yards and a trio of TD passes for Chicago.
The Titans (3-6) were led by Chris Johnson with 141 rushing yards and a touchdown on 16 carries. But the Tennessee star also lost two fumbles in the setback.
Matt Hasselbeck was held to 20-of-35 through the air for 194 yards, a touchdown and an interception for the Titans.