The visitors found themselves 1-0 ahead after less than a minute in the West Midlands thanks to Semi Ajayi’s tap-in, although that early initiative was lost after Joe Edwards’s neat header brought the hosts level in the 12th minute.
But the Millers ensured they remain just two points outside the top six ahead of their New Year’s Day clash at home against third-placed Blackburn Rovers when David Ball’s close-range finish just before the hour mark gave them a lead they never relinquished.
“It’s nice to win football matches and to finish the year with a win is great for us, especially on the back of the run we are having at the moment. It’s a good place to be,” said Warne.
“It wasn’t a classic, it was a little end-to-end. Both sides looked tired at times. In the couple of times, we were put under pressure, the lads put their bodies on the line and we did really well.”
The Millers took their early lead after Walsall failed to clear a free-kick, with Ball squaring across the face of the six-yard box for Ajayi to tap home.
But Luke Leahy’s 12th-minute cross picked out Edwards, whose bullet header flew into the top corner from 10 yards.
After the Saddlers missed a golden chance to go ahead before the break through Erhun Oztumer, they were made to pay when substitute Kieffer Moore had a telling impact – as has happened so many times this season – when his deflected header found Ball who bundled the ball home.
“It was a good start,” added Warne. “If we had capitalised on that and got another one, we could have had an easier day at the office.
“The goal they got was a good cross in and he finished it really well. They did not have enough threat to beat us. The change I made at half-time obviously had an impact and Kieffer came on and did what he does well, and he made the second goal.”
Walsall: Gillespie, Devlin, Kory Roberts, Guthrie, Leahy (Candlin 85), Ismail, Chambers, Edwards, Morris (Kouhyar 61), Oztumer, Agyei (Jackson 68). Subs Not Used: Liam Roberts, Wilson, Kinsella, Flanagan.
Rotherham United: Rodak, Emmanuel, Vaulks, Ajayi, Mattock, Forde, Frecklington (Wood 63), Towell, Williams, Yates (Moore 46), Ball (Newell 90). Subs Not Used: O’Donnell, Clarke-Harris, Ihiekwe, Cummings.
Referee: Graham Salisbury (Lancashire).