The former West Ham and Chelsea defender was signed by Redknapp for Portsmouth - initially on loan - in August 2006, with the right-back going on to make 84 league appearances for the Fratton Park outfit, winning the FA Cup in 2008 and establishing himself in the England squad.
And Johnson - who joined Liverpool for £18 million this summer and won a penalty against Spurs on Sunday - says he will forever be in debt to his former manager.
“It’s fair to say that Harry rescued my career. I wasn’t getting in the team at Chelsea. I asked to leave because I needed to play football regularly again," he said in the News of the World.
“Harry gave me a chance at Portsmouth when it was going wrong for me.
“He was the one that came to the table. He gave me an opportunity to rebuild my career and reputation at Portsmouth and I will always owe him something for the faith he showed in me.
“I have known Harry since I was a 10-year-old at West Ham and, of course, Portsmouth.
“He is a fantastic man and a great manager so I will always be grateful to him. He was the one who saw things in me."
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