Rooney retired from international football last week at the age of 31.
The Everton striker snubbed a return to the Three Lions squad and decided to pack it in instead after being told he would struggle to be considered for next summer's World Cup in Russia.
Rooney is England's all-time leading scorer with 53 goals as well as the most capped outfield star in history with 119 appearances.
He continues to divide opinion, with some people insisting he never proved himself at a major tournament.
But Defoe reckons this is rubbish and that Rooney is one of the true greats of English football.
The Bournemouth striker, who is in the England squad for the upcoming World Cup qualifiers against Malta and Slovakia, said:
"You have to respect his decision. He's retired at the top and you can sort of understand it because he's had such a great international career.
"He's done so much and has nothing left to prove. He will be missed.
"He's had a lot of criticism, but I think it's very strange because people don't understand what it takes to do it at that level.
"To be the highest scorer for England, well if that was me I'd be immensely proud.
"It's a wonderful achievement and you have to respect what he's done. He's a great guy as well and I wish him all the best for the future."
