The 67-year-old took over at Loftus Road in 2012 but was unable to save the west London club from relegation to the Championship.
Although they were lodged as favourites to secure an instant return, poor form around Christmas saw Redknapp's side having to face the play-offs to gain that much-anticipated promotion.
And it was during the play-off final win over Derby when Redknapp started to face the prospect of walking away - only for Bobby Zamora to score a last-gasp winner.
"If we hadn't gone up this year I would have turned it in," he admitted.
"I would have definitely packed up. I wouldn't have gone back and done another year in the Championship, it didn't appeal to me anymore.
"If we had got beat I would have turned it in, definitely.
"With 10 minutes to go I was thinking 'what golf club should I join this year - should I play here or there?' and then suddenly Bobby ruined it all."
Zamora’s strike was the saving grace that gave Redknapp the motivation to try again, and he is eagerly awaiting the new season and the challenges that come with top-flight football.
"Now I am excited again," he said.
"To go to Anfield and Old Trafford is fantastic, I am so lucky to be able to do that.
"I wouldn't have missed the Championship. I didn't fancy it. I would have said 'let somebody else have a go for a year' because I like the people here - I like the chairman, I genuinely look forward to seeing him."
Former England and Manchester United captain Rio Ferdinand is the only new recruit so far, and Redknapp is keen to add to his numbers before they kick off at home against Hull in just under a month.
"We'll get them in, we know that," he said.
"I'm not making it up. A couple of boys are training with us who are not with us and we have Adel (Taarabt), who looks like he's going to go.
"I've got a couple of kids playing with us to make up the numbers. We've got around 12, with a couple to come back. We'll be a maximum of 13 or 14."