Stella Hartley is not thought to have another role to go to, but will undertake consultancy work.
It was reported earlier this month that a restructure would lead to redundancies across the company, except in the sales department. The final number of job cuts is yet to be decided.
As yet, no replacement for Hartley has been announced, but the company says the marketing function will remain independent and will not be absorbed into any other division.
Hartley's departure comes three months after Gudjon Reynisson took over as chief executive from Nick Mather.
Chairman Stuart Rose also left Hamleys in July to focus on his other roles with lingerie firm Agent Provocateur and Gerard Restaurants.