During her time in Congress, Matsui has been an advocate for healthcare reform, environmental protection, and technology innovation.

Before her time in Congress, Matsui worked as a government affairs consultant and served as Deputy Assistant to the President in the Clinton Administration, where she worked with President Clinton to create the first White House Initiative on Asian Americans and Pacific Islanders in 1999.

Clinton appointed Matsui to the board of the Woodrow Wilson International Center for Scholars in September 2000.

Later, she became a lobbyist in Washington, representing corporate clients until 2005, when she decided to run for Congress against a field of local Democrats.

Matsui voted with President Joe Biden's stated position 100% of the time in the 117th Congress, according to a FiveThirtyEight analysis.

Matsui has advocated for access to reproductive health care by funding contraception programs and making them readily available.

[3] Matsui supports initiatives aimed at promoting sustainable infrastructure, providing tax incentives for clean energy, and reducing harmful emissions.

She voted to allow the EPA to regulate greenhouse gasses and promote strict limits to pollution levels for industries.

She supports banning large-scale purchases of ammunition and seeks to end the gun show loophole.

Matsui supports firearms manufacturers being held responsible for product misuse cases and lawsuits.

[3] In addition, Matsui has sought to expand medical coverage to children and the mentally ill. She voted against patients being denied treatment for non-emergency issues without a Medicare copay.

Matsui supports a progressive tax system and seeks to shut down offshore loopholes for business.

[3] Matsui favors continuing Social Security as it is now, and has opposed moves to privatize it or allow citizens the option to have alternative retirement funds.