The agency, which already handles the bulk of LG's advertising, will add strategy and execution for all brand marketing and product divisions to its remit. BrandBuzz's sister agency, Y&R Mexico, will also work on a portion of the new business.
The WPP companies pitched against Omnicom's Merkley & Partners for the business in a final shoot-out.
WPP holds a 49 per cent stake in LG Ad, LG's in-house ad division. The deal was struck in 2003 to ensure the business stayed in-house until the end of 2006.
LG has begun moving some of its business out of the internal agency.
In January, TBWA\Worldwide Seoul picked up the creative and promotions business in South Korea for two of its brands.