Mole Valley Council will get Â£21m from the developer Barratt Homes if the proposals go ahead.
Nearly 2,800 people have signed a petition against the sale of the allotments. Campaigners say schools and doctors surgeries are "already full".
Council leader Chris Townsend said the plans would provide more housing and financial support for council services.
There are more than 100 plots at the Barnett Wood Lane allotments.
The authority has said more than 100 allotment holders would get new plots and is suggesting a split site with allotments on both the Leatherhead and Ashtead sides of the M25.
Linda Weller, from the Leatherhead Poors' Allotment Society, who organised the petition, said the council had tried to address most of the issues the society had raised.
"We do still have issues with what we're being offered, " she said.
"We need time to go and assess both sites but we're slightly relieved that we're not going to the awful site that they originally dumped us on."
She said wildlife, including at least one badger sett, would be disturbed.
Allotment holder David Wells said local schools and doctors surgeries were already "rammed full" and that the roads were "a nightmare at the moment".
He added: "As a resident for over 60 years I've looked out at the allotments and now to be faced with 500 houses and the development prior to that, well it's not good news."
The Campaign to Protect Rural England (CPRE) Surrey said it would continue to campaign to protect green belt land and open spaces.
"We are extremely disappointed by Mole Valley Council's determination to dispose of a vital community asset and to allow building on adjacent green belt fields," the spokesman said.
"[The council's] approach to the Barnett Wood Lane site indicates a failure to think strategically about the role of Mole Valley's countryside and green belt.
"It also shows a woeful disregard for the needs of local people."
Five hundred homes could be built on allotments and green belt land next to the Leatherhead bypass in Surrey.