Gordon Campbell is one of the leading planning lawyers in London and acts for clients including housing and retail developers.
At Mishcons he will become head of planning and environment, joining a property department of 11 partners and 20 other fee-earners.
Head of property Nick Doffman says: "We have recognised for some time the increasing demand for specialist planning advice. Planning is an element of practically every property transaction we do.
"We have now bolstered this expertise with someone with the specialist focus and reputation to service those clients where planning and environmental issues are not just ancillary but pivotal to the project."
Campbell was a senior solicitor at Eversheds and joins Mishcons in the same position. His clients have included funders, developers, industrialists and public sector bodies, and he has particular expertise in advising the education sector.