The 66-year-old QPR boss believes Townsend is the closest player England have to Holland wing wizard Arjen Robben.
"If he can keep improving, I think the sky's the limit," Redknapp told Press Association Sport.
"It's up to him now. He's got a great chance.
"Andros is not Arjen Robben; he's not in his class at the moment, but he's very similar.
"He plays on that right side, likes to come in on his left foot when he can, he runs with the ball, he beats defenders, he tests the full-back."
What Townsend was lacking, until his spell at QPR, was sustaining strong performances.
"We loaned him out an awful lot because he couldn't get that consistency," Redknapp said. "He'd have a great spell for four or five games with a club and then his form tended to dip a bit.
"I brought him to QPR last year and he sustained that run of form throughout.
"That was the making of him. He proved he could play Premier League football week-in, week-out and could do it consistently well."
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