The agency has been charged with raising the firm's profile throughout European markets including the UK and the Netherlands.
As part of the brief, Bell Pottinger will seek to gain coverage for the views of WP Carey executives in the financial media.
'We will help communicate its business strategy, offer international deal support and raise the profile of the key European management team,' said Charles Cook, deputy chairman of the agency's corporate and financial practice.
The account was previously held by FD. WP Carey is a big player in the commercial property world, having a global portfolio exceeding $10bn (£5.5bn) in assets.
With corporates facing uncertain times, WP Carey is looking to promote itself as an alternative source of capital. The firm believes it can help companies and private equity firms release capital tied up in real estate via sale and leaseback-type financings.