“This is in essence creating a data broker division to Disney, expanding what Disney already knows, which is a lot,” said Jeffrey Chester, the executive director of the Center for Digital Democracy, a nonprofit consumer advocacy group. “You’re telling your entire life history to Mickey Mouse.”

Disney’s kingdom expanded this year as the conglomerate closed its $71.3 billion acquisition of 21st Century Fox assets. It opened a new area at Disneyland called Star Wars: Galaxy’s Edge that was the largest expansion in the park’s history, although attendance was disappointing.

On Nov. 12, the company will start its challenger to Netflix, Disney Plus. On Monday, a Twitter account for the streaming service spent nearly three hours posting a mega-thread of the titles that will be available on the streaming service, as varied as the beloved “Snow White and the Seven Dwarfs” and the more obscure “Zenon: The Zequel.” Earlier this month, Disney banned advertising from Netflix on its entertainment television networks ABC and Freeform.

In May, Disney freshened its strategy for deciding where and when to place its marketing and whom to target with it. The company spends more than $1.5 billion a year on media, according to the advertising research firm COMvergence. Disney’s media business up for bid was worth more than $2 billion.

Disney had been working with the ad groups Omnicom, Dentsu Aegis Network and Horizon when it put the contracts up for grabs. The pitch process was managed by the media consulting firm MediaLink and involved a flurry of presentations over a two-week period in Hong Kong, Dubai, Mumbai, London and Buenos Aires, according to two people familiar with the meetings. For Publicis, it was “the most important pitch of the year,” Mr. Sadoun said in his memo.

Publicis walked away with Disney’s media business for most of the world outside North America. In North America, Publicis will take charge of media strategy for the Disney Plus streaming service as well as Disney resorts and amusement parks.

Epsilon was a major draw because of the extremely detailed data it has compiled. The company may very well know if you are lactose intolerant or are in the market for a pickup truck with 60,000 miles on it. If you are into astrology or have taken out a home-equity loan, it may know that too.