The 63-year-old, who was the Celtic chief executive for 18 years, has returned to the club as the non-executive chairman and will start his new role next year onwards.
A Celtic man through and through, the club are hoping to reach new heights under his leadership again, but Bell stressed that he must not try to interfere with Postecoglou and his work.
The former shot-stopper is clear that the Celtic manager is still the main man at the club and he will continue to make all the big decisions when it comes to the football side of things at Parkhead.
Bell stressed that Lawwell would be wrong if he tries to interfere with the Celtic manager’s work and get himself involved in the football side of things.
The former Scottish Premiership star said on Clyde 1’s Superscoreboard: “I think Ange is a big character.
“For me, he has all the power in the football club. The way he came in and put his stamp on the football club and the way he has developed the club.
“I genuinely think he is still the man who will make all the decisions.
“Peter Lawwell would be daft to get involved in the football side of things, that is under control with Ange.”
Celtic have a nine-point lead at the top of the table but it has not stopped from Postecoglou from adding more quality to his squad ahead of the winter window.