During his tenure, Parrott organized efforts petitioning laws passed by the Maryland General Assembly to legalize same-sex marriage and extend in-state tuition to undocumented students, which were upheld by voters.

Parrott ran for the U.S. House of Representatives in Maryland's 6th congressional district in 2020 and 2022, losing both times to incumbent Democrat David Trone.

[4][2] Parrott first got involved with politics in 2002, successfully suing the American Civil Liberties Union over the removal of a monument for the Ten Commandments in a public park in Frederick, Maryland.

[5] In February 2013, Parrott was one of three House members who voted against reprimanding state delegate Tony McConkey, who failed to disclose a conflict of interest when pushing for legislation that would have allowed him to regain his suspended real estate license.

[9] In July 2012, Parrott founded an organization, MDPetitions.com, and started an accompanying website to coordinate efforts to petition laws he opposed to be placed on ballot initiatives.

In an interview with The Baltimore Sun, he said he started the website with the goal of "taming the Democratic establishment so it wouldn't pass legislation that most Marylanders oppose".

[4] That year, Parrott successfully placed ballot initiatives for three laws–the legalization of same-sex marriage, offering in-state tuition to undocumented immigrants, and the state's congressional redistricting map.

[14][15] In March 2013, Parrott joined a Judicial Watch lawsuit that sought to overturn the results of the 2012 redistricting referendum, asking the courts to hold a new election using different ballot language.

[16] In June 2015, Parrott joined another Judicial Watch lawsuit against Maryland's congressional districts, claiming that the state's redistricting plan was unconstitutional.

[19] In December 2021, Parrott and Judicial Watch filed a lawsuit that sought to repeal the state's newly redrawn congressional map, which he described as a "political gerrymander".

[22] In March 2022, Circuit Court Judge Lynne A. Battaglia ruled for Parrott, striking down the congressional maps that she called a "product of extreme partisan gerrymandering".

[37] Political analysts, including Goucher College's Mileah Kromer,[38] saw Trone's ability to self-fund and controversial Republican gubernatorial nominee Dan Cox as factors that led to Parrott's defeat.

[40] On June 27, 2023, Parrott formed an exploratory committee to explore a potential third run for the district in 2024, seeking to succeed U.S. Representative David Trone, who ran for U.S. Senate in 2024.

[53] In January 2025, Parrott formed an exploratory committee to explore a fourth consecutive run for the district in 2026, seeking to challenge U.S. Representative April McClain Delaney.

[64] In June 2022, Parrott celebrated the U.S. Supreme Court's ruling in Dobbs v. Jackson Women's Health Organization, calling it a "great decision".

[74][75] During the 2021 legislative session, Parrott introduced a bill that would require the Maryland State Board of Elections to verify signatures on mail-in ballots.

[83] In October 2024, Parrott said he supported the Keystone Pipeline[84] and cutting regulations to increase domestic energy production,[69] and criticized the Biden administration for reducing the amount of federal land that could be used for fracking.

[90] During the 2020 legislative session and following the 2018 Capital Gazette shooting, Parrott introduced a bill that would restore the death penalty in cases of mass murder.

[100] In March 2019, Parrott introduced an amendment to the state budget that would require the Maryland Department of Health to confirm an individual's immigration status before granting Medicaid benefits.

[55] He criticized the Bipartisan Border Security Bill negotiated by Senators James Lankford and Kyrsten Sinema, calling it a "non-starter" and would alllow 5,000 illegal immigrants to cross into the United States daily, and vowed to block federal funding for "sanctuary counties".

[84] He also blamed immigrants for high crime rates, economic instability,[99] housing prices in Washington County and promoted conspiracy theories claiming that the Federal Emergency Management Agency's response to hurricanes in North Carolina and the southeastern United States were hindered by the Biden administration of spending FEMA disaster relief funds on housing and food for illegal immigrants.

[106] In February 2024, he said he opposed removing Donald Trump from the 2024 presidential election ballot under the Fourteenth Amendment, saying that he believed that the January 6 Capitol attack was not an insurrection.

[66] During the 2014 legislative session, Parrott introduced a bill that would require law enforcement officers to read individuals their Miranda rights during a traffic stop and search.

[107] In 2020, Parrott introduced legislation that would exempt law enforcement officers who live in Maryland but work in other states from taking handgun training.

[59] In 2014, he opposed a bill to ban discrimination against transgender Marylanders in housing and employment, claiming it would "radically change our society and put our families and children at risk".

[112] In 2020, he expressed disappointment the U.S. Supreme Court's ruling in Bostock v. Clayton County, which held that the Civil Rights Act of 1964 also protected against discrimination on the basis of sexual orientation and gender identity, saying that he believed that Congress should have passed a law addressing the issue instead.

[60] In March 2005, Parrott wrote a letter to the editor for The Herald-Mail arguing that HIV-positive patients who are given life-saving medication should be tattooed "in a spot covered by a bathing suit" to prevent potential sex partners from becoming unknowingly infected.

During his run for the Maryland House of Delegates in 2010, he said he no longer supported the idea, citing advancements made in medicine to treat HIV.

[114][115] During the 2014 legislative session, Parrott voted for an amendment to the state budget that condemned antisemitism amid the American Studies Association's boycott of Israel.

[87] In 2017, Parrott opposed a federal bill that would remove a statue of Robert E. Lee from Antietam National Battlefield, claiming that its sponsors were "progressive Democrats who are trying to erase history".