Having replaced Kemar Roofe from the bench in the 86th minute, the 38-year-old striker managed to twist and turn in the box before beating Celtic goalkeeper Scott Bain in injury time to complete the scoring on a memorable day.
Defoe's fine finish was the icing on the cake for the Light Blues and to bag his first Glasgow derby goal was a special moment for a player who has achieved so much through his incredible career.
Speaking to RangersTV post-match, he said: "Obviously when you come to a club like this the Old Firm is the first fixture you look at and as a forward you just want to score in that game.
"The most important thing is to win those games, but if you can win and score it is just something I've always wanted to do to be honest, from the first day I walked into the football club.
"When it went in today it was an unbelievable feeling. it's always hard to describe the feeling because it is so special, but the team performance today was amazing. Every man was outstanding.
"Kemar for his second goal, when the ball went wide to Borna I just watched him and I knew he would score. The cross was unbelievable and we have got that quality from our full-backs, but the header was outstanding. It was a little bit behind him.
"For his first goal, people look at it and think it is lucky, but it is not lucky. Again it is being in the right areas and I am delighted for him.
"Buff also scored a fantastic goal. He was clever in the box, coming inside and finishing like that with his weaker foot. So yeah, it was good."
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