The former Kendall Tarrant chief executive stepped down from the board of the company's Hat Pin parent this week and will leave the operation in August.
Her departure follows the news in March that Kendall Tarrant was to merge with Stolkin + Partners, in a deal worth more than £1 million.
At the time, it was announced that Haines would become Kendall Tarrant's worldwide chairman, with an "ambassadorial" role.
Haines, 56, a one-time senior agency manager and a pivotal figure in some of the industry's most high-profile signings, said: "You have to know when to call time and I always said I would go while I was ahead of the game."
She said she had no firm plans but insisted she had no intention of setting up another headhunting company.
Her options include starting a Mark McCormack-style company to manage a number of the industry's top people. "It's a possibility," she added.
"I could also run a charity or even return to new business."
Terry Hitchcock, the Hat Pin non-executive chairman, praised Haines' enthusiasm, drive and commitment.