Barnes received a BA in Economics in 1975 from Augustana College, and an MBA in 1978 from Loyola University ChicagoBarnes has two sons and one daughter. She had a stroke in May 2010,[6] at a gym in Chicago,[6] which caused her to leave Sara Lee.[1][3] In 2012, Barnes was still getting phone calls about potential board openings but turned them down to focus on her health.[6] On January 15, 2017, she suffered another stroke and died two days later.[7] Brenda joined the Rehabilitation Institute of Chicago in 2014 as a distinguished member on the Board of Directors and the Identity Cabinet committee to help form and build the hospital branding and positioning.

After working as a business manager for Wilson Sporting Goods in 1976[3] and Vice President of Marketing for Frito-Lay in 1981, Barnes became Group VP of Marketing for PepsiCoin 1984.[3] She became President of Pepsi-Cola South/West in 1991, and COO of PepsiCo North America in 1993. Finally, in 1996, she became president and CEO of Pepsi-Cola North America in 1996, a job she left in 1997 to spend more time with her family, a move that made national headlines.[1][3] After PepsiCo, she spent time as interim president and COO of Starwood Hotels & Resorts, from November 1999 to March 2000, and as an adjunct professor, Northwestern University’s Kellogg School of Management and at North Central College in 2002.[4] In July 2004, she became president and COO of Sara Lee Corp. In February 2005, she became president and CEO of Sara Lee, and in October 2005, chairman and CEO. While there, Barnes moved Sara Lee's headquarters out of downtown Chicago to suburban Downers Grove. Barnes was on the board of directors of Avon Products, Inc.; Augustana College; Grocery Manufacturers Association; LucasFilm, Ltd.; The New York Times Company; PepsiAmericas, Inc.; Sara Lee Corporation; Sears, Roebuck & Co.; and Staples, Inc. She was also on the steering Committee of the Kellogg Center for Executive Women, Northwestern University.[2] While CEO of Sara Lee in 2008, Barnes earned a total compensation of $10,489,347, which included a base salary of $1,000,000, a cash bonus of $1,993,597, stocks granted of $4,866,000, and options granted of $2,398,668