ZenithOptimedia takes over the UK brief from PHD, which first handled the media account in December 1998.
The business includes an estimated £30m media planning and buying business in the UK, US, Australia, Singapore and Hong Kong.
It is understood ZenithOptimedia beat off challenges from sister WPP agencies Mediaedge:cia andMaxus 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 called on BBC Worldwide to curtail its operations.
They cited its acquisition of the Lonely Planet company in 2007 as having an adverse effect on its commercial competitors.
BBC Worldwide has expanded signficantly recently, making a profit of £118m in 2007/08, up from £37m in 2003/04.