Defoe has dropped down the Three Lions pecking order with just one goal being scored in 10 Premier League games this season, while Gareth Southgate has shown a preference to use younger players.
However, Howe has insisted that Defoe still has a role to play for England, provided that the 35-year-old can improve his form in front of goal during the rest of the campaign.
The 39-year-old is quoted by Sky Sports News as saying: "I believe that Jermain can make the World Cup squad. I think he can have an impact at the World Cup for sure. Obviously, it will be defined by how well he does for us between now and then.
"I think you need a mix of players to take to the World Cup. I'm not trying to tell Gareth anything, he will make his own decisions but I think everyone will recognise that you need leadership and experience and from Jermain's perspective someone who can change a game, come on and nick a goal, and who better than him?"
Defoe has scored 20 goals in 57 outings for his country, with the forward's last strike coming against Lithuania in March.