The Englishman joined Celtic under Brendan Rodgers last summer.
The 28-year-old has seven international caps under his belt but that haul does not look like improving any time soon.
The former Manchester City man endured a less-than-impressive last few years in the Premier League but enjoyed a huge upturn in fortunes after joining Celtic.
Sinclair reunited with Brendan Rodgers - whom he worked with at Swansea City - at the Hoops last summer and bagged a superb 25 goals in his first season.
But it remains to be seen whether England boss Gareth Southgate will recall him for the Three Lions, though Redknapp, now at Birmingham City, says he does not know why he no longer gets a look-in.
“Scott Sinclair’s a real talent,” he told The Scottish Sun. “I see the England team and I don’t know why he isn’t involved.
“I know he’s done it in Scotland this year but he’s a boy who I think has the ability to do it at the top level.
“Brendan’s got it out of him. That’s what happened at Swansea and now he’s had a great season at Celtic.”
The obvious answer to why the Celtic man is overlooked is the fact that he plays in Scotland, with the standard considerably lower than it is in the Premier League.
That being said, Redknapp knows a thing or two about footballers, having been a well respected manager for the guts of 30 years, and if he says that the former Aston Villa man has the ability to do it on the international scene then it's hard to disbelieve him.
To get in touch with a representative of Harry Redknapp for information, or to book the Birmingham City boss for public events, please visit: https://mn2s.com/booking-agency/talent-roster/harry-redknapp/
Celtic's Scott Sinclair scores their third goal