The appointments are effective immediately.
Mr Samworth previously served as managing director, EMEA, where he oversaw operational management of the region.
Mr Queenan previously served as chief operating officer for APAC.
As well as taking the new role, he will continue to serve as CEO of CBRE's development services subsidiary, Trammell Crow Company, a role in which he reports to Bob Sulentic, President and Chief Executive Officer of CBRE.
"These are well-deserved promotions for Martin and Danny," said CBRE CEO Mike Lafitte, "they are very talented executives who are highly regarded by our people in their regions."