By Jeff Horwitz and Deepa Seetharaman
Facebook Inc.'s board suffered another surprise departure with the exit of Jeffrey D. Zients, leading to an almost complete shake-up of the directors overseeing the social-media giant.
Facebook on Thursday said Mr. Zients wouldn't seek reelection after joining the board in 2018 as an independent director. He will be succeeded by Robert Kimmitt, a lawyer and former deputy secretary to the Department of the Treasury during the George W. Bush Administration, the company said after markets closed.
Mr. Zients was generally aligned with Kenneth Chenault, another Facebook board member that recently gave up his seat, according to people familiar with the matter. The Wall Street Journal reported earlier this month that Mr. Chenault resigned from the company's board following disagreements with founder and Chief Executive Mark Zuckerberg and other Facebook officials. They differed over governance at the company and its policies around political discourse.
Mr. Zients and Mr. Chenault are only the latest in a series of exits from the tech giant's board. In the past year, the company has announced the exit of five independent directors -- former White House chief of staff Erskine Bowles, Netflix Inc. CEO Reed Hastings, former Genentech executive Susan Desmond-Hellmann, former American Express chief executive Kenneth Chenault and now Mr. Zients -- replacing them in some instances with people who have pre-existing social or business relationships with Mr. Zuckerberg.
Billionaire investor Peter Thiel is the longest serving board member aside from Mr. Zuckerberg. He joined in 2005. Most other outside directors, aside from Marc Andreessen, a co-founder of the venture-capital firm Andreessen Horowitz,who joined in 2009, have been on the board two years or less.
Mr. Zients, an independent board member, will depart after Facebook's annual shareholder meeting, typically held in May. The company said he was vacating his seat "to devote more time to his business and other professional interests."
Mr. Zients, in a statement, said "I wish Mark, the leadership team, and the dedicated Facebook employees the best." A spokeswoman for Mr. Zients declined to comment further on why he was leaving.
Mr. Zients, a businessman and economic adviser to President Obama, served as the acting director of the Office of Management and Budget and was credited with helping fix HealthCare.gov, the health-care marketplace. After the Obama administration, he became president of the Cranemere Group, an investment holding company, and joined Facebook's board in 2018.
His successor, Mr. Kimmitt, is a lawyer who held numerous posts during the administrations of George H.W. Bush and George W. Bush, including deputy secretary of the Treasury, under secretary of state and ambassador to Germany. His name had previously surfaced as a potential appointee for various jobs within the Trump administration.
Write to Jeff Horwitz at Jeff.Horwitz@wsj.com and Deepa Seetharaman at Deepa.Seetharaman@wsj.com