A joint marketing agreement is a legal contract that governs the relationship between two or more companies to collaborate in advertising, promotion and sales. Joint marketing agreements are contracts that allow companies to market for each other and share audiences.Learn how to manage these agreements. Businesses form joint marketing agreements to gain market share. One company agrees to promote the other's products to its existing and future customers. The Houston First Corporation and Visit Houston award matching grants for local tourism-related marketing programs. See the program guidelines to apply. The Office of Business Opportunity oversees the administration of POP in partnership with each departments POP Liaison. ANNOUNCE JOINT MARKETING AGREEMENT FOR FUEL CELL BACK-UP POWER. Joint marketing agreements can be an invaluable tool for businesses of all sizes looking to maximize their potential.