The Richmond, Virginia-based, Interpublic Group-owned Martin Agency beat Bartle Bogle Hegarty, WPP Group's Young & Rubicam and Crispin Porter & Bogusky to win the account, after a pitch that began in August.
Gore created the Alliance for Climate Protection last year to educate the public on global warming, which he refers to as "the climate crisis". It came after his 2006 Academy Award-winning documentary 'An Inconvenient Truth', which raised the debate on the issue.
The request for proposal said that the Alliance needed an agency to create a three- to five-year "multi-media global campaign to transform awareness into action and advocacy".
It also called for a campaign of "commercial reach and scale, with budget parameters that rival major social marketing campaigns of the past" with a likely budget of at least $100m.
Spend on the campaign will rely largely on donations of money and media space.
Brian Hardwick, client communications director at the Alliance for Climate Protection, said that The Martin Agency was chosen because of its "ability to connect with regular people and we were impressed by their creative ideas".
Gore is chairman of the group's board, which also includes: Kevin Wall, Live Earth producer; Carol Browner, former US Environmental Protection Agency administrator; Larry Schweiger, National Wildlife Federation president and CEO; and Brent Scowcroft, a former national security adviser to Presidents Gerald Ford and George W Bush.