The Edinburgh-based agency said its specialism in planning sustainable events was key to winning the UK-wide tender.
Origin Events, which has worked on the UKELA conference since 2005, will continue to be responsible for sourcing the venue, planning a gala dinner and organising field trips for delegates.
The three-year contract requires the agency to provide locally-sourced food and use only venues that meet strict environmental criteria.
Origin Events director Denise Pinto said: "The last few years have proven that it is possible to plan a large conference in the UK that keeps an eye on the environmental impact of events management and delivers the necessary commercial returns."
Other clients to have appointed Origin Events include the Scottish Government, BSkyB, Standard Life and Thomson Reuters.