The 21-year-old midfielder is starting to blossom at the Etihad, having already won eight trophies.
Giggs won 25 honours with Manchester United, but Lescott thinks Foden could eclipse that mark.
"Regards to what he can achieve, hopefully, touch wood, he can withstand injuries, he can be the most decorated English player in history.
"What has he got? Two Premier League titles, an FA Cup, two League Cups. He's 20 years old. If he continues at this level and stays at City for the remainder of his career, which I hope he does, he'll average two, three trophies a season which is going to be remarkable."
Lescott added on Foden: "I don't think his quality is ever going to be in question. What he has, which I don't see many players have, is an obsession with football. I don't just mean love of the game - I love the game - but he's like weirdly obsessed with the game.
"He walks around with a football, I did some work with England Under-21s and I had to ban footballs from the hotel because he was constantly with one at his feet. He would want to stay extra on the field and do extra stuff so I had to monitor that. His obsession for football is none like I've seen before."