The striker scored an unorthodox opener – steering the ball past Scott Bain with his chest from around ten yards out.
A second-half header helped Rangers extend their advantage over Celtic’s ten men – and reminded Roofe who was the top team in Scotland this season.
Reflecting on the victory – which completes Rangers’ first unbeaten season against Celtic since 1999-2000 – the summer signing from Anderlecht said: “The result says it all, 4-1.
“We're champions but it was such a long time ago, we kind of forgot about that. I think this game has kind of brought it back to us.”
PLAYER RATINGS: Rangers rated after 4-1 Old Firm win over Celtic
His goals were a return to form for the striker, who has produced some memorable moments this season – including the halfway-line strike against Standard Liege in the Europa League – but recently missed a penalty against St Johnstone and has been slapped with a four-match European ban for being red carded against Slavia Prague.
But now there is renewed focus, and a target to achieve before the end of the season.
Speaking to Sky Sports he added: "The last five or six weeks have been frustrating for me, on and off the pitch things haven’t been going right for me. But this game – I’ve been preparing for it in my head for a long time.
"We won the league a long time ago, now it's about being unbeaten.
"Every game we try and play for something and that's what we've got to play for now.”