Rees is on gardening leave from EC&O Venues until January, when he is due to take the role of exhibition sales director at Excel London, having been poached last month.
Golden has spent seven years at EC&O Venues, most recently as event sales and marketing director.
Under her new title of commercial director, she will take responsibility for the exhibition sales department, as well as continue to lead the conference and event sales, and marketing and communications divisions of the two venues.
EC&O Venues group managing director Nigel Nathan said: "I am delighted that Anna has accepted the position of commercial director. During the past seven years, she has demonstrated her ability and commitment to the company."