Reed Exhibitions has sold three defence industry events, including DSEi, to Clarion Events.
DSEi (Defence Systems and Equipment International), ITEC and LAAD (Latin American Aerospace and Defence) were sold for an undisclosed sum.
The three shows have been sold as going concerns and the sale will involve the transfer of staff under TUPE arrangements, Clarion says.
Reed announced last June that it would pull out of the defence industry, citing incompatibility with its scientific and medical journals, including The Lancet.
Chief executive Sir Crispin Davis said at the time the defence shows are quality businesses.
"Nonetheless, it has become increasingly clear that growing numbers of important customers and authors have very real concerns about our involvement in the defence exhibitions business.
"We have listened closely to these concerns and this has led us to conclude that the defence shows are no longer compatible with Reed Elsevier's position as a leading publisher of scientific, medical, legal and business content."
Clarion Events is the largest independent event organiser in the UK.