Mars will buy the rights to the three brands in North America, Latin America and other regions excluding most European markets, the companies said in a statement on Wednesday.
The regions included in the deal account for about 80 percent of P&G Pet Care's global sales.
Mars, whose Petcare business includes brands such as Pedigree, Whiska, Banfield and Royal Canin, also has the option to acquire the brands in several other countries.
P&G said it was working on alternate plans to sell its Pet Care business in European Union countries.
P&G said it expected core earnings to be reduced by 3 cents per share in fiscal 2013 and by 4 cents per share in fiscal 2014 after it accounts for the business as a discontinued operation.
P&G said it did not expect the deal to hurt its forecast for core earnings growth per share for 2014 or have a material impact on 2015 results.
Mars, controlled by the Mars family, had annual sales of more than $33 billion in 2013 and was ranked 5th in Forbes' list of America's largest private companies. P&G had sales of $84.16 billion in 2013.
P&G shares were up in early trading on the New York Stock Exchange. (Get the latest quotes here.)