Defoe started his Premier League career at the Hammers, having joined them at the age of 16 in 1999, and became a regular in the first team at 18.
However, when the club were relegated from the top-flight of English football in 2003, he enraged fans of the East London club by handing in a transfer request within a day of being condemned to the Championship.
In a recent interview with the 'Transfer Talk' podcast, the Bournemouth striker revealed that his youthful ignorance was the reason for the decision, saying that his agent convinved him that it was the right thing to do.
"When I was young, I didn't really understand transfer requests, I had never come across one before and my agent told me it was the right thing to do," Defoe said.
"I trusted my agent and I thought this must be the process - hand in a transfer request and when you do that, you would be the first out the door, that's what he said to me."
While at the time Defoe was convinced that the decision was the right one for his career progression, he even remembers the then Chief Executive of the club questioning who had put him up to it.
"He was saying 'You don't need to do this because if a football club wants you, they will come and get you'. At the time, I thought I was doing the right thing, but looking back I'd change that 100 per cent. I think it's disrespectful."
Defoe left the club to go to Tottenham, where he had a successful four-year spell while West Ham returned to the Premier League after two seasons in the Championship under Alan Pardew.