Morris has become Brand Events' non-executive chairman in a move that reunites him with the organiser's managing director Chris Hughes. The pair worked together when Morris was Earls Court & Olympia's chief executive.
IMAC director Patrick McKenna sanctioned the deal, which leaves IMAC with a majority equity stake in the business and is believed to have included minor investment from Morris and the current Brand Events management team.
McKenna said: "We believe that current market dynamics, the quality of Brand Events and its excellent management team and the knowledge, relationships and financial resources of IMAC provide a unique opportunity to create the world's leading consumer events business."
Former Haymarket Exhibitions director Chris Hughes formed Brand Events in 1999. He said: "Ingenious is the ideal partner to support our growth plans. Its considerable media expertise will be an enormous asset in helping us expand Brand Events in the UK and around the world.
"With Andrew Morris, who is one of the most accomplished and dynamic figures in the industry, we firmly believe we can become one of the global leaders in the market over the next three to five years."