Begley is leaving the Good Relations Group agency for the associations in October, when he will take over from the departing Jace Tyrrell.
The associations are made up of more than 400 members comprising major owners, developers, investors and advisors in real estate in Central London.
They launched a cross-party manifesto in July titled 'Building Central London’s Future: A Manifesto for Growth', which will be taken to party conferences this September.
Begley will be tasked with taking the associations’ agenda forward in preparation for the upcoming key election years: the 2015 general election and the London mayoral election in 2016.
Daniel Van Gelder, chairman of Westminster Property Association, said: "Charles is ideally placed to build on the fantastic work Jace has done for the association and take the lead in our future strategy.
"His background in media and communications together with his knowledge of the property industry is a fantastic combination and we look forward to working with him."
Previous to his time as a senior partner with TTA, Begley was comms manager at Westminster City Council, taking the lead on media campaigns specialising in planning and regeneration issues.
He was also formerly a news editor at ITN, with a career in journalism that also includes stints at The Independent on Sunday, the London Evening Standard and News International.