James Addison Baker III is a prominent Republican lawyer and statesman, born into Houston's elite establishment. His father, James A. Baker Jr., was a partner at the Baker Botts law firm known as 'The Warden' for his strict demeanor, and his mother was Bonner Means Baker, a socialite. His grandfather, James A. Baker (1857–1940), served as personal attorney to William Marsh Rice and long-time chair of Rice University's Board of Trustees. He earned a Bachelor of Arts in History from Princeton University in 1952 and an LL.B. from the University of Texas School of Law in 1957. Baker served as a U.S. Marine Corps officer (active 1952–1954, reserve 1954–1958), attaining the rank of Captain, including as a naval gunfire spotter aboard USS Monrovia in the Mediterranean during the Korean War.

He married Mary Stuart McHenry in 1953 after meeting on a Princeton rugby trip to Bermuda; she died of breast cancer on February 18, 1970, leaving four sons: James Addison Baker IV (b. 1954, partner at Baker Botts), Stuart McHenry Baker (b. 1956, Baker Global Advisory), John Coalter Baker (b. 1960), and Douglas Bland Baker (b. 1961). He married Susan Garrett Winston in 1973; they had daughter Mary Bonner Baker (b. 1977), and he is stepfather to Winston's three children from her prior marriage. His sister, Bonner Baker Moffitt, predeceased him in 2015 after struggles with schizophrenia. Granddaughters include Virginia 'Graeme' Baker (d. June 15, 2002, at age 7 in hot tub suction entrapment, inspiring the Virginia Graeme Baker Pool & Spa Safety Act) and comedian Rosebud Baker.

In his early career, Baker was a partner at Andrews, Kurth, Campbell & Bradley (1957–1980), specializing in corporate law, mergers, and acquisitions for clients like Petro-Tex Chemical and oil heirs. A close tennis friend of George H.W. Bush at Houston Country Club, his wife's death prompted political involvement. He managed local campaigns, including Bush's 1970 Senate run (loss to Lloyd Bentsen) and as Nixon's 1972 Texas finance chair. He served as Under Secretary of Commerce (August 2, 1975, to May 7, 1976) under Ford, advocating textile protections and delegate wrangling at the 1976 RNC, and later as Ford campaign chair. He was the unsuccessful Republican nominee for Texas Attorney General in 1978, losing to Mark White.

Baker served as White House Chief of Staff and U.S. Secretary of the Treasury under President Ronald Reagan, and as U.S. Secretary of State under President George H.W. Bush. Post-government, he was a senior partner at Baker Botts L.L.P., senior counselor at The Carlyle Group (1993–2005), and consultant to Enron (1993–1995). He founded and serves as honorary chair of the James A. Baker III Institute for Public Policy at Rice University (1993), acted as UN Personal Envoy for Western Sahara (1997–2004), U.S. Special Envoy for Iraqi Debt Relief (2003, securing $100B restructuring), and co-chaired the Iraq Study Group (2006, bipartisan with Lee Hamilton). He has held advisor roles with the U.S.-Azerbaijan Chamber of Commerce, Atlantic Council, and as foreign policy advisor to Jeb Bush's 2016 campaign, and co-founded the Climate Leadership Council (post-2017) with a carbon tax proposal.

An avid hunter (pheasant, turkey, safari), he owns 1,555-acre Silver Creek Ranch near Boulder, Wyoming (purchased post-1988 election) and resides primarily in Houston.

Controversies include his Enron consultancy (1993–1995) involving a Kuwait power plant deal and criticized for conflicts; scrutiny over Carlyle Group influence and access peddling (resigned 2005); leading the Bush team's legal strategy in the 2000 Florida recount, accused of irregularities (denied); blamed for Gulf War diplomacy missteps (1990–1991); harsh 2015 comments on Netanyahu causing issues for Jeb Bush's campaign; and minor lawsuits (e.g., Herbert L. Miller v. Treasury, 1991; Thomas v. Baker). No criminal convictions or major personal legal issues are documented.