It is understood ZenithOptimedia beat off challenges from sister WPP agencies MEC and Maxus to win the account. PHD withdrew from the pitch in September.
The account encompasses the corporation's magazines, audio books, DVDs and digital media.
ZenithOptimedia will deliver media campaigns around the BBC's key brands such as Top Gear, BBC America and Doctor Who.
Its appointment comes as BBC Worldwide looks to drive significant growth outside the UK.
The company hired I-Level to work on its search marketing in March last year, after a pitch against undisclosed agencies.
In April this year, MPs in the UK called on BBC Worldwide to curtail its operations.
BBC Worldwide has expanded signficantly recently, making a profit of £118 million ($198 million) in 2007/08, up from £37 million in 2003/04.
BBC Worldwide Channels Asia will launch four thematic channels on Hong Kong Cable by the end of 2009.