The appointment was made without a pitch after the incumbent on the business, United London, was closed by its parent, WPP, last month.
Nick Hurrell, the Hurrell and Dawson co-founder, said: "The Early Learning Centre is an inspirational company with fantastic products that help children explore their creativity and make learning fun. It is deservedly the leading brand in its market; we're delighted to be working with it."
News of the appointment comes in the same week as Mothercare finalised a deal to buy ELC for £85 million, uniting two of Britain's best-known children's and parenting retailers.
Mothercare, whose advertising account is held by St Luke's, confirmed on Monday that it would buy ELC's parent company, Chelsea Store Holdings, for £49 million. At time of going to press, it was unclear if the sale would affect the relationship with either agency.
The account is the latest to move from the defunct United London's locker. It follows Sky's £80 million move to WCRS, COI's Food Standards Agency and Home Office accounts' switch to Grey and Singapore Airlines' move to TBWA\London.
The appointment follows an increased period of activity in the educational toy market. Last month, the US toy brand LeapFrog Enterprises, appointed TBWA\London to develop a strategic positioning for the brand.
Chelsea Store Holdings is owned by Tim Waterstone, the founder of the Waterstone's bookshop chain. It also runs Daisy & Tom, a small chain of department stores for children, which is being retained by one of the shareholders.