The Bees legend started work on the stadium project in 2003 and became a Bees United director, helping the trust, run by Brian Burgess, take over the club from Ron Noades, raising over £6million.
Gammon also worked on the partnership agreement in Matthew Benham, which was completed in March 2010 before leading the purchase of the Lionel Road site from Barratt in 2012.
Working alongside Burgess, they helped the club secure planning permission to build the stadium and around the site.
With Brentford now starting work on the stadium Gammon feels his key role has been completed and has decided to tender his resignation.
He said: “Now that the land acquisition and planning consent have been successfully secured and preparatory work on site has begun, my key role has been completed.
“I am immensely proud of Bees United's role in acquiring the Club from Ron Noades, the partnership and subsequent sale to Matthew Benham, the progress made in bringing our plans for the new stadium at Lionel Road to fruition and my contribution to these achievements.
“Combined with the significant progress made on the pitch, underpinned by Matthew's support, it has been an exciting time to work for and support the Club.
“As a Bees fan I am looking forward to next season and of course beyond to the opening of the new stadium."
Gammon will now be an associate director of Brentford FC, in recognition of his sterling work for the football club over the last 14 years.
Bees chairman Cliff Crown said: “On behalf of everyone at the Club and all our fans I would like to thank Chris for his commitment, dedication and the enormous contribution he has made to the Brentford Community Stadium project over many years.
“We would not be in the position we are in today if it was not for the work, some five years of it on a voluntary basis, that Chris – together with Brian – put in.
“We owe Chris a huge debt of gratitude for his efforts. In recognition, the Club has offered and Chris has accepted a position as a Brentford FC Associate Director.”