The midfield marvel drilled a low shot beyond goalkeeper Conrad Logan on 11 minutes to cap an impressive display.
The Robins should have added to their tally before half-time with Luke Garbutt forcing Logan into a hurried save when he let fly with a 35-yard effort.
Bagasan Graham drilled a shot across the face of goal on 18 minutes while Jimmy Spencer crashed a header just wide of the target on the half-hour.
After a promising opening ten minutes, Rotherham struggled to create anything of note before the break, Lewis Grabban going closest when he dragged a shot wide after holding off defender Steve Elliott.
The Robins continued to make chances after the break with Spencer hitting the outside of the post midway through the half before substitute Kaid Mohamed, on the pitch for less than a minute, was denied by a full-length save.
The Millers were denied a penalty however when Michael Raynes was hauled down in the area but referee Langford waved away appeals.
Cheltenham keeper Scott Brown was forced into action late on to keep out a Brett Williams header at full stretch but the home side ran out winners.
Source: DSG