Subject to completion of two separate consultation processes, the transaction is expected to close in the next four to six weeks.
The deal will see Briefing Media pick up titles including Farmers Guardian, Dairy Farmer, Pulse and Practical Commissioning, their associated websites and a number of medical events and seminars.
The portfolios combined employ 90 staff, based in Preston and London, and generated £12.1 million in revenue last year.
UBM has retained ownership of the Cropworld conference and the Chemist & Druggist magazine and data product portfolio.
Briefing Media was set up by Neil Thackray and Rory Brown in 2010. It runs TheMediaBriefing site which provides aggregation, analysis, comment and events for the media industry.