The 31-year-old moved from Tottenham to Toronto in February and has been a hit in the MLS, scoring 11 goals in 16 appearances.
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Redknapp was keen to bring Defoe back to England but was unable to conclude a deal before the transfer window shut on Monday. However, he is confident of sealing the striker's signature in January.
"There is every chance he will come in January," Redknapp told talkSPORT. "I'm a big fan of Jermain's. Almost certainly, I think we will [go back in for him].
"I've signed him so many times. I've taken him everywhere."
Redknapp revealed that Defoe did want to come to QPR but added that Toronto was not willing to let the player go during the MLS season.
"We tried all day with Jermain Defoe," he added. "He was keen to come. We agreed a deal with Toronto but they wouldn't release him now.
"We could do a deal and then take him in January but we wanted to get someone in [on Monday]."