Defoe struck his fifth goal in seven appearances for Toronto since joining the MLS club from Tottenham in January, thumping the ball into the top-right corner of the net after just 11 minutes against New York Red Bulls.
England manager Hodgson announced his 23-man squad for the FIFA World Cup on Monday and could not find a spot for Defoe, instead naming Wayne Rooney, Rickie Lambert, Daniel Sturridge and Danny Welbeck as his strikers.
While Defoe was put on England's reserve list - meaning he could be promoted if one of the initial 23 are injured - the 31-year-old could not contain his disappointment on Friday.
"I don't think I'll ever be at peace (with the decision)," the striker said.
Defoe added: "When you've been involved in every squad and the World Cup comes around and you're not in the 23, it's hard to understand."
That was why Saturday's goal against the Red Bulls, which set up Toronto's 2-0 win, was so important for Defoe.
"It's only normal when you get a disappointment to try to prove people wrong, and just to remind people, at the end of the day, this is what I'm doing," he said.
"I think I did that today."
Defoe, who has scored 19 goals in 55 games for England, missed all of April with a hamstring strain.
The veteran striker returned earlier this month in the Canadian Championship, helping Toronto into the final, and in his first MLS appearance since March, scored in front of his home fans.
When Toronto midfielder Bradley Orr stole possession and burst forward, Defoe took off, collecting a pass from his teammate and then crunching his shot in off the crossbar.
"Do you know what, it's quite funny because I didn't actually see the ball go in," Defoe said.
"As I went through, I was confident I was going to score, and as I hit it, I think the defender hit me after I got the shot off.
"I was on the floor and I sort of looked at the crowd and saw everyone celebrating so I thought, 'ok, that went in."
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