Maloney was elected to the New York City Council in 1982, defeating incumbent Robert Rodriguez[11] in a heavily Spanish-speaking district based in East Harlem and parts of the South Bronx.

[14] She was the first person to give birth while serving as a council member, and the first to offer a comprehensive package of legislation to make day care more available and affordable.

In December 2008, Maloney hired a public-relations firm to help bolster her efforts to be named by Governor David Paterson as Hillary Clinton's successor in the U.S. Senate.

Public opinion polls placed Maloney's support for the Senate seat in the single digits, trailing the front-runner, then-State Attorney General Andrew Cuomo, although her bid was endorsed by the National Organization for Women Political Action Committee, the Feminist Majority Political Action Committee,[20] New York Times columnist Nicholas Kristof,[21] and other columnists[22] and editorial boards.

In the Democratic primary for Congress on September 14, 2010, Maloney defeated a well-funded opponent, Reshma Saujani, a 34-year-old Indian-American hedge fund lawyer, by 62 percentage points.

[44] In 2011, a Daily News survey found that Maloney ranked first among New York's 28 representatives for activity with 36 proposed bills, resolutions, and amendments.

Her efforts prompted Wayne Barrett of the Village Voice to write that Maloney was "like a tiger in the House on every dollar due New York.

[56] After the 9/11 Commission published its findings, Maloney co-founded the bipartisan House 9/11 Commission Caucus[57] and helped write and secure the enactment into law of many of its recommendations to reform the nation's intelligence agencies[58][59] Congressional Quarterly wrote in its annual guide, 2006 Politics in America: "In the 108th Congress, Maloney reached out beyond her usual roles as a liberal gadfly and persistent Bush administration critic, helping win enactment of a sweeping bill to reorganize U.S. intelligence operations.

"[60] Following the Dubai Ports World controversy, Maloney helped secure the passage and enactment of her bill to reform the system for vetting foreign investments in the United States.

[63] On October 1, 2020, Maloney co-signed a letter to Secretary of State Mike Pompeo that condemned Azerbaijan’s offensive operations against the Armenian-populated enclave of Nagorno-Karabakh, denounced Turkey’s role in the Nagorno-Karabakh conflict, and criticized "false equivalence between Armenia and Azerbaijan, even as the latter threatens war and refuses to agree to monitoring along the line of contact.

"[64] Maloney, who chairs the House Oversight and Reform Committee, called on FBI Director Christopher A. Wray to open a probe into social media platform Parler, writing, "The company was founded by John Matze shortly after he traveled in Russia with his wife, who is Russian and whose family reportedly has ties to the Russian government.

"[67] In 2022, as chair of the House Oversight and Reform Committee, Maloney held a hearing that examined leading gun manufacturers' marketing and sales practices.

[68] Maloney introduced a bill in October 2003 intended to enforce transparency in relation to military contracting in Iraq and subject the Coalition Provisional Authority to federal procurement law.

[69] In 2008, after reports of corruption among military contractors in both Iraq and Afghanistan, she secured House passage of a further bill to create a database to better monitor all federal contracts, the key provisions of which were adopted into law as part of the defense budget.

[72] In 2019, Maloney introduced a bill that would require corporate entities to disclose the identities of beneficial owners to FinCEN, making it harder for them to hide assets and avoid taxes through a series of limited liability companies.

[74] She advocated for providing federal support for medical monitoring and health care for rescue and recovery workers who were exposed to toxic smoke and dust at the Ground Zero site after the 9/11 attacks.

In June 2012, it was announced that the program would be expanded to cover care for a variety of cancers of the lung, trachea, stomach, colon, rectum, liver, bladder, kidney, thyroid and breast.

After a prolonged and very public push, a total of $8.5 billion in funding was included in the Omnibus Spending bill that passed in 2015 and extended the life of the monitoring and health insurance coverage for 75 years.

A 2014 Social Science Research Network study estimated that since its passage, the CARD Act has saved consumers $11.9 billion per year.

The legislation would impose dramatically tougher ethics rules for the Minerals Management Service, which was at the center of a major corruption scandal stemming from its employees' relationships with oil company representatives.

The effort to enact the bill was later the subject of a Lifetime Television movie, A Life Interrupted: The Debbie Smith Story,[100] in which Maloney was played by Lynne Adams.

[104] In 2008 and again in 2009, Maloney authored, and secured House passage of, a bill to provide four weeks of paid parental leave to federal employees.

[110] Maloney has helped secure funding for major mass transit projects, resulting in the commitment of billions of federal dollars for New York State.

In a New York Times op-ed, Michael Eisen said the bill would force the public to pay $15–$30 per paper to read the results of research they had already paid for as taxpayers.

[116][117] On February 27, 2012, following a boycott of the organization, Maloney wrote to her constituents, "it is important to be mindful of the impact of various industries on job creation and retention.

[119][120] In 2021, Maloney protested the expansion of the New York Blood Center, a nonprofit biomedical research facility, from a three-story-headquarters to a 16-story tower on Manhattan's Upper East Side.

"[152] Muslim-American Rana Abdelhamid, while running in the Democratic primary against Maloney in 2021, criticized this event as feeding negative stereotypes about Muslims and of "weapon[izing my identity] to justify American wars".

[154] At the time, she was a week away from announcing an official campaign against Gillibrand in the 2010 United States Senate Democratic Primary election in New York.

And he said, 'It was like saying nigger to a Puerto Rican,'Civil rights activist Al Sharpton criticized the remark and called Maloney's casual use of the word "alarming" but said he did not believe she was racist.

[162] In a February 2022 report, the Office of Congressional Ethics said it found "substantial reason to believe that Rep. Maloney may have solicited or accepted impermissible gifts associated with her attendance at the Met Gala.