Collison played 105 games for the Hammers, scoring 11 goals, including crucial strikes in the Championship Play-Off semi-final victory over Cardiff City in 2012.
The Watford-born former Wales midfielder grew up idolising Chelsea, the team of his late dad, but that did not stop him growing to love the supporters of one of their fiercest rivals.
After graduating to the West Ham first team from the club's famous Academy under Alan Curbishley, Collison was one of the hottest prospects around.
But a series of devastating injuries restricted his playing time and nearly ended his career.
After a year in the wildnerness without a club, Collison - who has been training to be a sports journalist - has recently made the first tentative steps in a return to the game with Peterborough United.
And in an emotional article he penned himself for the Independent, the 27-year-old has lifted a lid on the moment West Ham fans sealed a place in his heart forever.
'The night the football family came together'
It came back in August 2009 and against the Irons' arch rivals Millwall in a League Cup match. But more importantly, it was just days after the then 21-year-old's dad had been killed in a motorcycle crash on his way to watch his son play for the Hammers.
"It’s hard to explain exactly how I felt, but I decided to play in a cup game and I knew it was the right thing to do," Collison wrote in the Independent.
"It was a massive game against Millwall, our local rivals, and I knew my dad would have been there cheering me on under the lights at Upton Park.
"It was such an emotional night and one that I will never, ever forget.
"This was the night the football family came together.
'They carried me through'
"My team-mates, the staff and the West Ham fans carried me through what was the toughest game of football I have and ever will play in.
"The intense feelings were very different. It’s hard to find anything that can make you feel 10-feet tall when all you want to do is roll up into a ball and cry and let the world swallow you up."
Collison is hoping that he can resurrect his career with the Posh, for whom he has featured eight times since signing a one-year deal with the club where he first started out as a youngster back in May.
He is also the coach of the club's Under 21 side, as he bids to add as many strings to his bow as possible given the troublesome time he has had with injuries over the years.
One thing is for sure, West Ham fans will be wishing him every success.