The King Arthur Baking Company, formerly the King Arthur Flour Company, is an American supplier of flour, ingredients, baking mixes, cookbooks, and baked goods. It also runs two baking schools, one at its Norwich, Vermont, bakery and the other in Burlington, Washington.

The company was founded in Boston, Massachusetts, in 1790 before the headquarters was moved to Norwich, Vermont. It is the oldest flour company in the United States. King Arthur Baking is employee-owned and a B Lab-certified benefit corporation.

The company was founded in 1790 in Boston, Massachusetts, by Henry Wood. Wood was primarily an importer and distributor, originally of English-milled flour. The business grew quickly, and Wood took on a partner in the early 1790s, forming Henry Wood & Company. Benjamin F. Sands took over the company in 1870, renaming it to reflect his ownership interest. In 1895, the company was reorganized as a joint-stock company, named Sands, Taylor & Wood Company after its then owners: Orin Sands, Mark Taylor, and George Wood (no relation to Henry Wood).

In 1896, Sands, Taylor & Wood introduced a new brand of premium flour. George Wood had attended a performance of the musical King Arthur and the Knights of the Round Table, which inspired the name of the new product: King Arthur Flour. The brand was introduced at the Boston Food Fair on September 10, 1896, to substantial commercial success.

With Orin Sands's death in 1917, control of the company passed to his son, Frank E. Sands. As the market for retail flour declined, the company expanded into the commercial bakery market, first with wholesale flours and later (in the 1960s) into commercial baking equipment. Sands, Taylor & Wood also introduced other retail food products under the King Arthur name, including a line of coffee.

Sands, Taylor & Wood acquired Joseph Middleby, a maker of baking supplies, such as prepared pie fillings, in 1973. Three years later, that business was expanded with the purchase of H.A. Johnson. As interest rates rose through the 1970s, financial pressures forced the company to change strategy, and in 1978 then-president Frank E. Sands II sold off all but the core flour business and relocated the company from Brighton, Massachusetts, to Norwich, Vermont. As of 1990, the company had only five employees; it hired its sixth that year, P. J. Hamel, who was brought in to increase the company's sales outside of New England, including developing a catalog.

Co-owner Brinna Sands, wife of Frank Sands II, is credited with starting the bakery and school; according to the former director of the Norwich retail bakery and baking school Jeffrey Hamelman, she was "a visionary. She's the one who felt like King Arthur would never be a truly complete company just selling flour. It's got to be showcasing what the flour can do."

Sands, Taylor & Wood Company converted to an employee-owned business structure in 1996, and also changed its name to The King Arthur Flour Co., Inc., reflecting its principal brand. The company has been 100% employee-owned through an Employee Stock Ownership Plan (ESOP) since 2004. Employees who log more than 800 hours of work per year following their first year of employment are eligible to become owners through the ESOP. In 2007 it became a B corporation.