Mullin was born on July 26, 1977 in Tulsa, Oklahoma. He graduated from Stilwell High School in Stilwell, Oklahoma. He attended Missouri Valley College in 1996, but did not graduate. Mullin received an associate in applied sciences degree in construction technology from Oklahoma State University Institute of Technology, in 2010.
Mullin took over his family's business, Mullin Plumbing, at the age of twenty, when his father fell ill. He also owns Mullin Properties, Mullin Farms and Mullin Services.
He hosted House Talk, a home improvement radio program, on Tulsa station KFAQ and syndicated across Oklahoma.
Despite describing the American Recovery and Reinvestment Act of 2009 as a "horrible waste of tax dollars", his plumbing business, which he inherited from his father, accepted contracts of approximately $370,000 in government funding from that program.
Incumbent Democratic U.S. congressman Dan Boren decided to retire in 2012. Mullin declared his candidacy for the 2012 elections to the United States House of Representatives to represent Oklahoma's 2nd congressional district in September 2011. In the six-candidate Republican primary, Mullin ranked first with 42% of the vote, failing to reach the over 50% threshold. State representative George Faught ranked second with 22% of the vote. In the run-off primary election, Mullin defeated Faught 57%–43%.
The second has historically been a classic "Yellow Dog" Democratic district. However, it has steadily trended Republican, as Tulsa's suburbs have spilled into the northern portion of the district. For these reasons, Mullin was thought to have a good chance of winning the election. In the general election, Mullin defeated the Democratic candidate, Rob Wallace, a former district attorney, 57%–38%. He became the first Republican to represent the district, since Tom Coburn in 2001, and only the second since 1921.
On February 5, 2014, Mullin introduced the bill To revoke the charter of incorporation of the Miami Tribe of Oklahoma at the request of that tribe (H.R. 4002; 113th Congress), which would accept the request of the Miami Tribe of Oklahoma to revoke the charter of incorporation issued to that tribe and ratified by its members on June 1, 1940.
In April of 2017, Mullin drew criticism when he was recorded during a town hall meeting telling his constituents that it was "bullcrap" that taxpayers pay his salary. He said, "I pay for myself. I paid enough taxes before I got here and continue to through my company to pay my own salary. This is a service. No one here pays me to go.” According to the January 2012 Congressional Research Service, the salary of a U.S. representative is $174,000 per year, and benefits include allowances, cost-of-living adjustments, enrollment in a pension, health benefits, personnel, mail and office expenses, and a travel allowance.
During the 2012 campaign, Mullin promised to serve for only three terms, totaling six years. However, in July of 2017, Mullin released an eleven minute video announcing that he would indeed run for a fourth term, saying he was ill-advised when he made the promise to only serve three terms.Committee on Natural Resources
Subcommittee on Indian and Alaska Native Affairs
Subcommittee on Water and Power
Committee on Transportation and Infrastructure
Subcommittee on Economic Development, Public Buildings and Emergency Management
Subcommittee on Highways and Transit
Subcommittee on Water Resources and Environment
He and his wife, Christie, live in Westville, a few miles from the Arkansas border, and have five children. He is an enrolled member of the Cherokee Nation, and is one of two Native Americans in the 113th Congress. The other Native American is fellow Oklahoma Republican Tom Cole, a member of the Chickasaw Nation.
Mullin is a former professional mixed martial arts fighter and is listed in the Sherdog Fight Finder with a 3-0 professional record.