A victory was desperately needed at the end of a trying February, during which the Millers had failed to claim a single win.
Joe Rafferty struck after seven minutes to give Matt Hamshaw’s men the lead and Plymouth were unable to produce a response.
It was not a case of the hosts clinging on for dear life either, as the Millers continued to probe in search of a two-goal cushion.
A second goal may have eluded them, but there were jubilant scenes at the full-time whistle when victory was secured.
Here are The Yorkshire Post’s ratings from the New York Stadium.
5. Emmanuel Adegboyega - 6
Steady enough before succumbing to injury after just 36 minutes. | Jonathan Gawthorpe
6. Reece James - 8
Defensively solid and managed to wreak some havoc with his wand of a left foot. | Harriet Massey/Getty Images
7. Josh Benson - 7
Threatened from set-pieces and looked assured on the ball before making way early in the second half, presumably for fitness-related reasons. | Pete Norton/Getty Images
8. Dru Yearwood - 7
Got better as the game went on. Made some really important defensive interventions. | Jonathan Gawthorpe