The 66-year-old managed the young forward for several years at Tottenham before then taking him on loan at Loftus Road last season, where he flourished despite the Rs' relegation.
"He was fantastic for us in the time he was at Rangers," Redknapp told the Sunday Mirror. "I think it was the making of him.
"He showed that he get the better of a number of Premier League defences. I also decided to switch him. He was always on the left but I decided to play him on the right and he made an even bigger impact.
|12/1||Andros Townsend is 12/1 with Bet365 to score the first goal in an England win over Poland
Townsend has started eight of Spurs’ 12 games so far this season, finally breaking into the first team at White Hart Lane, but Redknapp does not feel that he waited too long to give him a taste of the Premier League.
"Yes, I let him go on loan a lot [while I was Spurs boss] but that was because I had Gareth Bale and Aaron Lennon as my regular wide players at Tottenham," he argued. "I took Andros to Europa League matches but he wanted to be playing on a regular basis.
"There was nothing wrong with his character or anything like that. The opposite, in fact. Tim Sherwood had a word for him when he was taking the younger players. Tim called him 'relentless' and that just about sums him up.
"Andros was relentless in his ambition to make it. The loan deals were good for him. It showed him football from another view.
"That he has done well for Tottenham and now England is no shock to me. He has so much talent and a brilliant attitude."