Brooke, who started at the agency this week, will set up a new team at Elephant and report to founder Guy Bellamy.
She will draw on 27 years' worth of experience working with clients such as The Four Seasons London and the Cartier polo tournament.
Bellamy commented: "We don’t follow a sector or channel model at Elephant; our service lines are based on key skill areas that clients may call on to support their in-house team.
"Events have not to date been a formal service line, but it’s now a natural move for us and Nicky will develop a series of services here that fit our firm’s culture and approach to doing things differently."
Brooke will be working on client events such as The Association of Financial Mutuals' annual conference.
Her hire comes a month after that of Paul Bellamy as creative director to lead work in digital comms and branding.