[4] Both his parents were public school teachers, and he was raised in suburban areas, growing up in the largest city in Berkshire County.

[5][6][7] Fallon earned his bachelor's degree in government and international relations from the University of Notre Dame,[1] where he played varsity football under coach Lou Holtz and was part of the 1988 national championship team.

He is the president and chief executive officer of Virtus Apparel, a company that specializes in clothing of military and patriotic design.

[10][11] In 2009, Fallon launched a campaign that netted him 57% of the vote to defeat three opponents for an at-large seat on the Frisco City Council.

In the Denton County portion of Frisco, which consists of about one-third of the voters in House District 106, Fallon polled 65% of the vote.

[14] Fallon co-authored a 2013 Texas law that allows students and employees of independent school districts to say "Merry Christmas" rather than the secular "Happy Holidays".

[15] Fallon ran unopposed for the Republican nomination in 2014 and defeated Democrat Lisa Osterholt and Libertarian Rodney Caston in the general election with 24,419 votes, almost 70% of the total.

[1] Fallon defended his "Merry Christmas" law in an appearance on David Barton's WallBuilders Live radio program, telling co-host Rick Green, a former member of the Texas House from Hays County in suburban Austin, that those offended by public schools hosting Christmas parties should examine their own hearts to evaluate their attitudes.

[24] Fallon opposed the bill to establish a taxpayer-funded breakfast program for public schools; the measure passed the House, 73–58.

[25] The PACT ACT which expanded VA benefits to veterans exposed to toxic chemicals during their military service, received a "nay" from Fallon.

[28] In 2018, Fallon was criticized[29] for his remarks about state representative Mary González, an openly pansexual woman, while delivering a speech to the local Wichita County Republican Women's group.

[33][24] In May 2020, Fallon launched a campaign for Texas's 4th congressional district to replace former U.S. representative John Ratcliffe, who resigned to become Director of National Intelligence.

On January 6, 2021, Fallon, along with 147 of his fellow congressional Republicans, voted to block certification of the results for President-elect Joe Biden's 2020 United States presidential election.

[37] In March 2023, Fallon was one of 26 Republicans sitting on the House Oversight and Accountability Committee who refused to join their Democratic counterparts in signing a letter denouncing white supremacy and racist conspiracy theories.

[42] Fallon reversed course the next day, even after his potential return to the Texas Senate received an endorsement from Lieutenant Governor Dan Patrick, and announced that he would instead seek reelection to his current House seat after all.

[43] On July 29, 2024, Fallon was announced as one of seven Republican members of a bipartisan task force investigating the attempted assassination of Donald Trump.

[44] In February 2022, the Office of Congressional Ethics (OCE) board filed a report stating that there was "substantial reason to believe" that Fallon had violated a federal stock law.

This non-cooperation undermined the OCE's ability to verify Rep. Fallon's overall STOCK Act compliance and to fully assess the reasons for his late filings.

On March 18, 2022, one of his lawyers, Kate Belinski, sent the OCE a letter insisting that Fallon's beliefs were "a common misconception, which, coupled with the overwhelming amount of information new members and their staff receive at the beginning of their terms, often results in inadvertent late disclosures."