Granger was born in Greenville, Texas, and grew up in Fort Worth. She attended local public schools and Eastern Hills High School. She graduated from Texas Wesleyan University.
Granger taught high school English and journalism for several years and became familiar with many issues in the community. In 1978 she decided to establish her own insurance agency, which she operated for years. Deciding to become active in local politics, Granger was elected to the Fort Worth Zoning Commission. she was elected to the city council in 1989. She was elected Mayor in 1991 in a non-partisan election as the first woman mayor of the city.
After Congressman Pete Geren announced he would retire in 1996, both the Democratic and Republican parties worked to recruit Granger to run for his seat. Republicans were bullish on their chances of winning Texas' 12th congressional district. It had once been represented by Democratic Speaker of the House Jim Wright, but legislative redistricting after the 1990 census had added areas with more Republican residents.
Granger decided to run as a Republican, much to the dismay of local GOP activists, who criticized her as being too liberal. She won handily, taking 56 percent of the vote over the Democrat Hugh Parmer, also a former Fort Worth mayor. She was reelected in 1998 and faced serious opposition only in 2000. In 2008, Granger defeated Democratic challenger Tracey Smith with 67 percent of the vote.
In 2006 Granger published a book, What's Right About America, Celebrating Our Nation's Values, reflecting on lessons from prominent figures of United States history.
That year, she was reelected to her sixth term in Congress. She was elected as Conference Vice Chair, the fourth-ranking position among House Republicans, in November 2006. She is Chairwoman of the House Appropriations Subcommitee on State-Foreign Operations. She also sits on the United States House Committee on Appropriations's Subcommittee on Defense (the first woman to do so), and the Labor, Health, Human Services, and Education Subcommittee. She has also served as a House Deputy Whip.
On September 25, 2007, she publicly endorsed former Massachusetts governor Mitt Romney in the primary race for the Republican Party presidential nomination. She also took up the position of national co-chair of the campaign organization Women for Mitt, filling a vacancy left by the death of Jennifer Dunn. In a statement to the press following her endorsement, she said that she had heard Romney speak and that "I agreed with everything he said, in the order he said it."
She is a member of the Board of Directors of the International Republican Institute. and Southwestern University. She is also a member of the Council on Foreign Relations.Committee on AppropriationsSubcommittee on Defense (Chairwoman)
Subcommittee on State, Foreign Operations, and Related Programs
Subcommittee on Energy and Water
Anti-Terrorism Caucus (Co-Chair)
International Conservation Caucus
Iraqi Women's Caucus (Co-Chair)
Congressional Arts Caucus
Her website has an article from "Conservative Quarterly" that describes her as "a dependable vote for the leadership on most issues." She is a member of the conservative Republican Study Committee.
In 2003, Granger was given a 10 percent rating by NARAL and an 84 percent rating by the Christian Coalition of America.
Granger has voted several times in favor of an amendment to the United States Constitution to make it a crime to physically desecrate the American flag. She supports the Federal Marriage Amendment to define marriage as only permitted between a man and a woman.
She was renominated in the March 2, 2010, Republican primary, having polled 70 percent of the ballots over intraparty rivals Mike Brasovan and Matthew E. Kelly.
In 2012, after chairman of the Taiwanese defense committee Lin Yu-fang rejected calls for more F-16 fighters and said that only the F-35 could ensure Taiwan's security, Granger offered a NDAA amendment, which passed the House, to offer only the much older F-16 fighter to Taiwan.
In June 2013, Granger was among the members of Congress who voted to pass an amendment to the National Defense Authorization Act for Fiscal Year 2014. The amendment would continue to restrict the Pentagon from entering into new contracts with Russia’s state arms broker, Rosoboronexport.
During her tenure, Granger has supported more than $50 million in earmarks to infrastructure projects in Fort Worth that benefited the Trinity River Vision Authority, an organization headed by her son.
Granger has three children and five grandchildren.In August 2007, Kay Granger Elementary School, named in her honor, opened in far north Fort Worth in the Northwest Independent School District.
Kay Granger Park was named for her. It is a city park located next to Mullendore Elementary, named for her mother, which was opened several years earlier in North Richland Hills.
She was elected to the Texas Women’s Hall of Fame and the Fort Worth Business Hall of Fame.
She received the National Federation of Independent Business’ Champion of Small Business Award; the Manufacturing Legislative Excellence Award from the National Association of Manufacturers; as well as the Lifetime Achievement Award from the Greater Fort Worth Home Builders Association.
In 1993, her high school recognized Granger as a distinguished alumnus.