The former West Ham and Tottenham forward has played a crucial role for the Black Cats in 2016, but he has still been overlooked by Roy Hodgson, Sam Allardyce and Gareth Southgate in their respective England squads.
Defoe helped Sunderland survive relegation last season and he has also scored plenty of goals to lift them off the bottom of the table during the current campaign.
He has scored 17 goals so far in 2016 and he secured his 150th in the Premier League during last week's 3-0 win over Hull.
Some sections of the press have claimed Defoe will continue to miss out on a place in the national squad but the former FC Toronto striker believes he is still capable of playing for his country.
He told Goals on Sunday: "As a forward, if you're scoring goals, you get in the squad. It has been like that over the years if you look at the great goalscorers this country has produced, it's always about playing well, scoring goals and being fit.
"I'm not sitting there saying that I should be playing for England but if someone said to me do you think you're good enough to get into the squad, I would say yes."