Hendricks was born and raised in Wisconsin, the daughter of dairy farmers. She graduated from Osseo-Fairchild High School in 1965, and had been divorced from her first husband for ten years when she met Ken Hendricks.
In 1975, she was selling custom-built homes and Ken was a roofing contractor. They married and became Business partners. In 1982, they used their lines of credit to secure a loan that enabled them to establish ABC Supply. ABC Supply is privately held, and sells roofing, windows, gutters, and siding for residential and commercial buildings.
She has produced movies, including The Stoning of Soraya M. (2008), about an execution in an Iranian village, An American Carol, (2008), and Snowmen, (2010).
Hendricks paid no state income tax in four of the five years from 2010 to 2014.
She donated $500,000 to Governor Scott Walker's 2012 campaign to avoid recall, and was his biggest donor that year. She also supports Paul Ryan. In 2014, she donated $1 million to the Freedom Partners Action Fund, a pro-Republican Super PAC created by the Koch Brothers. In both 2015 and 2016, she donated $2 million to Freedom Partners Action Fund. In 2015, she gave $5 million to a PAC associated with presidential candidate Scott Walker, but has had $4 million refunded.
In the 2016 U.S. presidential election, she gave over $5 million to the Reform America Fund, a super PAC which has opposed Hillary Clinton and supported Republican U.S. Senator from Wisconsin Ron Johnson. Hendricks served as an economic advisor to Donald Trump's presidential campaign.
She is a donor to WisconsinEye, and co-chair of Rock County 5.0, a five-year public/private initiative to advance Rock County’s economic development vision. She has served on the boards of the Stateline Boys & Girls Club, Beloit Memorial Hospital, the Beloit Foundation, Forward Janesville, Kandu Industries, Blackhawk Bank, and the Hendricks Family Foundation. Hendricks serves on the Board of Trustees of Beloit College.