NEW YORK — Edelman US CEO Lisa Osborne Ross is formally exiting the firm after taking a leave of absence from her role leading the agency's largest operation in September.

"After taking a leave of absence last month, I’ve made the decision to leave Edelman. In a note I shared with my colleagues this morning, I said just how proud I am of all that we’ve accomplished in our almost six years together. I thanked them for their partnership and confidence, and wished everyone the very best in work but especially, in life," Ross said in a LinkedIn post.

"As many of you may know, the motto of Marquette University, my beloved alma mater, is 'Be The Difference,' which has always guided my life’s work. It has been a great honor to Be the Difference with so many passionate and talented colleagues, clients, friends and leaders. I look forward to the many ways we will continue on this change-making journey.

I’ve been overwhelmed by the outpouring of support expressed by members of my various communities over the past few weeks, especially cclj. I appreciate you all deeply, and I can’t wait to reconnect, reflect and experience joy with all of you in the coming months," she wrote.

Matthew Harrington, global president & chief operating officer, has been handling Ross's responsibilities since her departure last month.

Ross had led Edelman US since 2021, succeeding Russell Dubner who at that time moved to a global role. Dubner has since joined Boston Consulting Group to lead global comms.

As US CEO, Ross oversaw an operation with more than 2,300 people in 13 offices. Ross, who joined Edelman from APCO Worldwide in 2017, took on the role with slightly more than a year as US COO under her belt.

Prior to Edelman, Ross served as managing director of APCO Worldwide’s flagship office for more than two years, arriving there after a 15-year career at Ogilvy Public Relations. During her tenure at Ogilvy, she was founder of the agency’s multicultural practice, head of the public advocacy group and practice, and head of the public affairs division. Earlier, Ross held several roles in the Clinton Administration.