A member of the Democratic Party, he previously served as the Genesee County Treasurer from 1996 to 2013, before succeeding his uncle, Dale Kildee, in Congress.

He was one of four candidates to challenge incumbent Mayor Matthew Collier in the August 6 nonpartisan primary election.

[8] In 2002, Kildee helped create the Genesee County Land Bank, a Washington D.C.–based nonprofit organization focused on urban decay.

[12][13] In 2009, Kildee co-founded and served as president of the Center for Community Progress, a nonprofit focused on urban revitalization.

His fellow freshmen Democratic members elected Kildee to serve as their representative to the caucus's Steering and Policy Committee.

[20] He supported Steny Hoyer's "Make it in America" legislation, which would remove tax breaks for companies that move jobs overseas.

[22] Congress passed a funding measure that provided $170 million in aid to communities including Flint that sought infrastructure improvements for their water.

[23] Kildee voted with President Joe Biden's stated position 100% of the time in the 117th Congress, according to a FiveThirtyEight analysis.

[27] In September 2022, he hosted a reproductive rights roundtable alongside Representative Sara Jacobs in Midland, Michigan.

[38] Kildee introduced legislation that included a provision for a $7,500 tax credit for electric vehicle buyers.

1944: The Private Property Rights Protection Act of 2014, which would have prohibited government use of eminent domain for the purpose of economic development.

[41][42] In April 2018, Kildee, Jared Huffman, Jamie Raskin, and Jerry McNerney launched the Congressional Freethought Caucus.

The bill would allow history books to go into more depth on African American struggles and set up a reparations commission for those with enslaved ancestors.

[49] In 2022, Kildee was among the representatives to sign a letter calling on President Joe Biden to lift tariffs on China.

[64] On March 31, 2023, Kildee announced that he had been diagnosed with squamous cell carcinoma, saying that a "very small tumor" had been found in one of his tonsils.