Informa revealed plans to save £60 million a year from the tie-up and said there would likely be some job losses as it looks to cut out overlapping management roles.
But the group stressed it would be a “relatively small number” of the 11,000 combined workforce and was largely set to affect head office only.
The deal - which is due to complete in the second quarter - sees the revival of takeover plans that fell through a decade ago.
Under the cash-and-shares offer, Informa investors own 65.5% of the company and UBM shareholders 34.5%, in line with terms of the tie-up announced earlier this month.
Stephen Carter, chief executive of Informa, said: “It is clear that the B2B (business to business) market is moving to operating scale and industry specialisation.
“Our recommended offer for UBM promises to create a leading B2B information services group with the international reach and market capabilities to take full advantage of these trends.”
Mr Carter will become chief executive of the combined firm, with Informa chairman Derek Mapp holding on to his position at the head of a board of seven non-executive directors.
Informa added that Patrick Martell, its chief executive of business intelligence, will take over from UBM boss Tim Cobbold to lead UBM as an operating unit through to commercial integration at the end of 2018.
Mr Cobbold and UBM chief financial officer Marina Wyatt will then step down within a month of the merger.
Under Mr Cobbold, UBM has exited non-core operations to focus on its events business.
It sold its last magazine title, the construction industry publication Building, earlier this month.
UBM also owned Express Newspapers, Property Week, The Publican and Music Week, but has shifted its focus on events, conferences and exhibitions, such as fashion shows in the US and jewellery expositions in the UK.
Informa specialises in B2B events, business intelligence and academic publishing, and has a presence in North America, South America, Asia, Europe, the Middle East and Africa.