Worts, currently director of comms at the department, will start her new role in the new year, replacing Stephen Thornton as UK director of external affairs.
She joins as Chancellor George Osborne battles claims that government policy could lead to a housing market bubble.
Osborne spoke out after fears raised by Business Secretary Vince Cable, with RICS suggesting a five per cent cap on house price rises.
Worts' departure follows more than two-and-a-half years at Defra, which she joined having headed up corporate comms at DECC.
She will report into Mark Walley, RICS’ regional MD, EMEA, who said: "Our Royal Charter includes the clause to work with government and Parliament on property and land issues in the wider public interest. Kim’s background working at the heart of government will enhance our ability to communicate on the role of our professional standards with ministers, officials and stakeholders.
"She joins in January 2014 at a time when the property sector will be key to sustain economic growth, and as all political parties seek to develop policy proposals on housing, land, construction and infrastructure en route to the general election in 2015."
A replacement has yet to be recruited, but interim arrangements will be announced shortly.