A member of the Democratic-Farmer-Labor Party (DFL), Greenman represents District 63B, which includes parts of south Minneapolis in Hennepin County, Minnesota.

She then worked as an attorney in the Public Defender's Office in Ramsey County, Minnesota, and as a state director for the Service Employees International Union.

In 2015, she represented Tony Webster, an independent journalist who sued the city of Bloomington for failing to release records related to a Black Lives Matter protest.

[11] She is the author of the "Democracy for the People" Act, the House DFL's major elections bill of the 2023 legislative session.

[14] She has sponsored legislation to increase protections for poll workers and to tighten reporting requirements for independent political expenditures.

[18] She also wrote a bill to restrict who can be classified as an "independent contractor" to protect Uber and Lyft workers from exploitation.