Warne, who was part of Rotherham's double promotion seasons of 2000 and 2001, suffered a broken bone in that last start and only appeared as a substitute on a few occasions towards the end of last season.
Now 37, he also has coaching duties but still regards himself very much as part of the squad. "The gaffer knows I want to play but I didn't really expect to do so when Tom Elliott pulled out with an injury," said Warne. "I was just so pleased to be out there and it was great to get the winning goal as well."
Manager Ronnie Moore enthused: "He's looked after himself, he's so fit and dedicated and he is an excellent pro."
The decisive moment came a minute from half-time. A quick throw-in saw Adam Le Fondre turn the ball across the area where Warne dived to head his first goal for exactly a year.
In a tight contest against Simon Davey's big, physical Hereford side, it gave Rotherham something to hold on to during a frenetic second half.
Andy Warrington denied Sean Canham right at the start of the second half and Rotherham had big escapes when Stuart Fleetwood and O'Neil Thompson shot wide.
Warrington again excelled with a save from James McQuilkin as Rotherham battled to a fine win.
Hereford United: Bartlett; Green, Kovacs, Townsend, Valentine; Colbeck, Thompson, Lunt, McQuilkin; Fleetwood, Canham. Unused substitutes: Rose, Stratford, Connor, Gwynne, Kanoute, Thomas, Weir.
Rotherham United: Warrington; Holden, Geohaghon, Cresswell, Newey; Law, Harrison, Taylor, Ellison (Bradley 85); Warne (Marshall 80), Le Fondre. Unused substitutes: Green, Ashworth, Mullins, Ani, Annerson.
Referee: S Rushton (Staffs).
Man of the match: Paul Warne.