The council has taken home the top prize at the UK Real Estate Investment Infrastructure Forum Awards.
The authority published its first environmental policy statement in the 1980s.
Since then, a number of sustainable developments have been built.
These include the nation’s first major zero-carbon community, BedZED, in Hackbridge in 2002.
The large-scale, mixed-use sustainable community comprises 100 homes, office space, a college and community facilities.
In 2019, the Council declared a climate emergency and ambitions to achieve net zero carbon emissions by 2030.