Boyhood Celtic fan Robbie Keane joined the Bhoys on loan until the end of the season in a deal that will see him earn ₤65,000 ($103,500) a week.
The Irish striker was welcomed by a huge group of Celtic supporters, who were celebrating the arrival of one of the biggest stars to the club in some time.
After falling down the pecking order at Spurs, Keane decided it was time to move on. However, the decision to leave England and move north to Scotland was somewhat of a surprise.
Redknapp said: "It's a good move. Robbie needs to play.
"He's too good a player not to be starting here regularly. He wants to play all the time.
"It's been difficult to guarantee Robbie a starting place at the moment.
"He's not a happy man when he's not playing regularly.
"But he loves his football; he's a great trainer, a great man about the place."
Keane's move was the biggest deal of the January transfer window for soccer transfers.
The Irish international could make his debut Tuesday night against Kilmarnock.