Ilo Browne Wallace (March 10, 1888 – February 22, 1981) was the wife of Henry A. Wallace, the 33rd U.S Vice President and later Secretary of Commerce. She was the Second Lady of the United States from 1941 until 1945. She was the sponsor of the USS Iowa (BB-61).

Born in Indianola, Iowa, she was the daughter of James Lytle Browne and his wife, the former Harriet Lindsay.

She attended Monmouth College with the class of 1911.

She married Henry Agard Wallace in Des Moines, Iowa, on May 20, 1914. They had three children: Henry Browne Wallace (1915–2005), Jean Browne Wallace (1920–2011), and Robert Browne Wallace (1918–2002). Her husband later became the editor-in-chief of Wallace's Farmer, an influential Midwestern farming magazine that had been founded by his father, Henry Cantwell Wallace, a future U.S. Secretary of Agriculture.

A small inheritance she received from her parents enabled the Wallaces and their business partners to establish, in 1926, Hi-Bred Corn Company, which developed and distributed hybrid maize and eventually transformed agriculture. The company is now known as Pioneer Hi-Bred International, the world's second largest seed company.

She died at the Wallace estate, Farvue Farm, in South Salem, New York.