IPG Mediabrands’ global chief Eileen Kiernan steps down as Omnicom Integration takes hold

The sweeping Omnicom–IPG merger continues to reshape the leadership landscape across the newly combined holding company. Eileen Kiernan, CEO of IPG’s media arm, IPG Mediabrands, is set to exit as the network is folded into Omnicom Media, according to an internal memo cited by Adweek.

Kiernan’s departure is among the most significant aftershocks of Omnicom’s $13 billion acquisition of Interpublic Group, completed last week. The integration has already triggered thousands of layoffs, the retirement of three legacy agency brands, and a wide-scale executive realignment. 

The India-arm of the Mediabrands also witnessed the shuffle. Executive chairman Shashi Sinha has been made “strategic advisor” while CEO Amardeep Singh has been given COO’s role at Omnicom. As part of the consolidation, IPG Mediabrands ceases to exist as a standalone unit, absorbed into Omnicom’s unified media structure. 

In her memo, Kiernan acknowledged the depth of the transition underway: “As IPG Mediabrands evolves into the next chapter of Omnicom Media, regrettably we will be saying goodbye to a number of our people, including some of our global leaders,” she wrote, thanking teams for their commitment during a turbulent period.

Kiernan also disclosed that after 14 years at IPG, she too would move on—but only after staying through the first few months of 2026 to support a smooth handover to Omnicom Media CEO Florian Adamski.

Having taken over as CEO of IPG Mediabrands in 2023, following a five-year stint leading the network’s Johnson & Johnson business globally, Kiernan said additional changes would be communicated soon. She reiterated the combined company’s commitment to client excellence, investment in connected capabilities, and the rollout of a unified operating model. Kiernan declined to comment; Omnicom representatives also did not provide a statement.

Adamski—who has led Omnicom Media Group since 2021—will spearhead the expanded media operation, now referred to simply as Omnicom Media. The new division will house six network agencies: OMD, PHD and Hearts & Science from Omnicom, alongside UM, Initiative and Mediahub from IPG.

Its commercial backbone will be driven by Omnicom Media Investment, Outdoor Media Group, and IPG’s Kinesso, while Acxiom and Omnicom’s Annalect will anchor the data layer. A set of specialist units—Omnicom Media Health, Ptarmigan, TRKKN, Optimum Sports, Fuse, and influencer agency Creo—will also sit under the new structure.

Leadership of Omnicom Media will be dominated by former Omnicom executives, with select IPG leaders stepping into key roles. Justin Wroe, formerly IPG Mediabrands’ U.S. CEO, will become chief commercial officer, while Daniel Fox and Jonathan Rigby will continue as chief investment officer and chief strategy officer, respectively.

Industry analysts expect the combined entity to significantly expand its principal media buying ambitions—potentially influencing the flow of billions in global ad spend.