Tenure
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.
Fallon voted to include provisions for drafting women in the National Defense Authorization Act of 2022.
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.
Fallon was among the 71 Republicans who voted against final passage of the Fiscal Responsibility Act of 2023 in the House.
Fallon voted to provide Israel with support following 2023 Hamas attack on Israel.
On November 13, 2023, it was reported that Fallon had filed to run for the state senate seat he once held, opening up his congressional seat in the 2024 election. 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.
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.
On December 5, 2024, acting Secret Service director Ronald L. Rowe Jr. testified before Congress, taking responsibility for the agency’s failures and outlining corrective measures. He announced initiatives including enhanced technical assets, expanded staffing, improved retention efforts, and a new "chief wellness officer" to support mental health. These reforms aimed to address gaps in intelligence, communication, and protective protocols. Fallon criticized Rowe for not deploying additional protective units and for his absence from the rally site after the attack. Rowe refused to answer questions, emphasizing ongoing improvements and rejecting claims of politicizing his role. This eventually led to a shouting match between the two, before Pennsylvania Representative Mike Kelly ordered the two to get back in order.