The body, run by transport commissioner Bob Kiley, believes a long-term campaign is required to soften public opposition to the charge ahead of its introduction, scheduled for mid-February.
TBWA/London is creating the campaign, which is likely to cost up to £15m and include TV, radio, press, online and outdoor advertising. Triangle Communications is handling below-the-line work.
London Mayor Livingstone is due to give final approval to congestion charges pending the outcome of two 'readiness reviews' relating to public transport and technology.
Last weekend, TfL marketing chief Charles Monheim, a US citizen, became involved in a high-profile row when he was mentioned in a national newspaper article accusing Kiley of hiring a 'band of cronies'.
TfL's corporate marketing account is handled by M&C Saatchi. It was also appointed to the congestion charging business, but controversy over the appointment led to a repitch, which TBWA won.