Visit Brighton has won bids to host events for mental health charity Mind and the Chartered Institute of Public Relations (CIPR).
It follows the city's successful bid to host the Summer Eventia conference, announced in February.
Summer Eventia will take place on 5-7 July this year, the Mind event will run from 25 to 27 November this year, and CIPR is planning an event for October 2010.
The three events combined are expected to deliver more than £1m of economic benefit to the city.
"In a tough operating environment winning three new contracts of this size in the space of a few weeks is a real boost to Brighton," said Julia Gallagher, convention bureau manager at Visit Brighton.
"Our new business pipeline is also positive for the remainder of the year and into 2010, with some landmark conferences expected to confirm over the next few months."