Publicis Groupe closed on its deal to acquire data-marketing behemoth Epsilon on Tuesday for a cash consideration of $4.4 billion with a net purchase price of $3.95 billion.

"This is an important day for us," Publicis CEO and Chairman Arthur Sadoun told Ad Age, claiming that the integration of Epsilon across its four networks—Publicis Communications, Publicis Media, Publicis Sapient and Publicis Health—has been "outstanding."

Effective immediately, Publicis will begin rolling out Epsilon to its U.S. clients. International clients will gain access to its services in the coming months. In previewing the data-tech platform to clients, Sadoun claimed it has received "a warm welcome."

Epsilon will be Publicis' sole data-tech platform, with Publicis PeopleCloud being folded into it. Epsilon will be run by its current CEO Bryan Kennedy.

Sadoun said what differentiates Epsilon from other data platforms like San Francisco-based LiveRamp, is that it benefits from Publicis having the "scale to bring it to life." He said clients will benefit from Epsilon working across Publicis "in a seamless way," championed by the holding company's Power of One model.

Publicis Communications will tap into Epsilon's customer insights to create more relevant campaigns and adapt to "real-time consumer context." Publicis Media will be connected to Epsilon's data sets to build consumer IDs, segment audiences and maximize return on investment for clients. Publicis Sapient will have access to proprietary customer insights for the optimization of clients' businesses. Epsilon will partner with Publicis Health to "deliver outcomes-based measurement and optimization across strategic, creative and media engagements," according to the company.

Every Publicis client will eventually be able to access Epsilon through their respective account leaders.

Publicis added that it created 19 operational task forces to address issues such as data privacy, real estate and support functions.

"It is a challenge to bring data, creativity and technology together," Sadoun said. "But if you do it right, which we are, you bring value to your clients. We don't want [Epsilon] to be siloed, we want it to be the heart of the company."