[2] Ramirez-Rosa is a member of the Chicago City Council's Progressive Reform Caucus,[3] and was elected to serve as a delegate to the 2016 Democratic National Convention as a Bernie Sanders supporter.

[14] He is the nephew of Cook County Judge Ramon Ocasio III,[15] and Chicanas of 18th Street author and activist Magda Ramirez-Castaneda.

[29] Ultimately, Ramirez-Rosa joined with Mayor Rahm Emanuel to sponsor and pass a $21 million property tax rebate program.

[32] He joined all five other members of the Socialist Caucus in signing a letter to Lightfoot which criticized her budget for "an over-reliance on property taxes" and "regressive funding models" that are "burdensome to our working-class citizens, while giving the wealthy and large corporations a pass.

He championed the construction of a 100-unit, all-affordable transit-oriented development to replace a city-owned parking lot next to the Logan Square Blue Line station.

[43] In 2021, he sponsored successful ordinances to establish minimum density requirements,[44] and a demolition impact fee for portions of his ward facing high displacement.

[46] He has supported historic preservationist efforts in his district, including the allocation of $250,000 in public landmark funds to help restore Logan Square's Minnekirken.

"[50] Ramirez-Rosa has consistently expressed his belief in participatory democracy as central to his work as a democratic socialist elected official.

"[52] In 2019, Ramirez-Rosa explained to writer Micah Uetricht how he seeks to put participatory democracy into action in his elected office: "In the thirty-fifth ward we have what we call 'people-power initiatives.'

"[53] The three "people-power initiatives" Ramirez-Rosa supports through his elected office are "community-driven zoning and development" - a local participatory planning process,[53][54][55] participatory budgeting for the allocation of infrastructure improvement dollars,[56] and a local rapid-response deportation defense network called the "community defense committee."

[62] The new ordinance – Empowering Communities for Public Safety – passed the Chicago City Council on July 21, 2021; Ramirez-Rosa was a chief sponsor.

[64] In December 2017, Ramirez-Rosa was the sole member of the Chicago City Council to support the No Cop Academy campaign, a grassroots abolitionist effort to stop the city from spending $95 million on a new police academy building and instead spend that money on education, after school programs, job training, and social services.

Our nation has witnessed the magnitude of police crimes in the City of Chicago with the murders of Rekia Boyd and Laquan McDonald.

The $95 million that the City is projected to spend on this new cop academy should be invested in jobs, education, youth programs, and mental health services, not a new shooting range and swimming pool for police.”[66] In May 2018, after successfully delaying a vote on the new police academy, Ramirez-Rosa was expelled from the Chicago City Council's Latino Caucus.

[72] Ramirez-Rosa's office distributed a bilingual newsletter to 7,000 ward households to provide residents with information on unemployment insurance and resources available to support them during the pandemic.

[81][82] In 2017, Ramirez-Rosa sponsored and passed an ordinance to designate Kedzie Avenue in his ward as "Lucy Gonzalez Parsons Way," in honor of the late labor organizer and founder of the IWW union.

"[83] In 2016, Ramirez-Rosa sponsored a successful measure to ensure transgender persons had the right to access the public bathroom of their choice.

[88] As Johnson's Floor Leader, Ramirez-Rosa was tasked with whipping votes on the City Council for the mayor's agenda, including securing the passage of One Fair Wage legislation raising the minimum wage for tipped workers, doubling the number of guaranteed paid leave days for Chicago workers, and placing a referendum on the ballot to create a dedicated revenue stream to address homelessness by raising the real estate transfer tax on properties that sell for over $1 million.

[90][89] In his role as Johnson's Floor Leader, Ramirez-Rosa worked to prevent the meeting and the effort to strip Chicago of its sanctuary status from moving forward.

[90] Immediately following the adjournment of the meeting, alderman Ray Lopez claimed Ramirez-Rosa, in order to prevent a quorum from being present "layed hands", grabbed, "manhandled" and "physically blocked" alderwoman Emma Mitts from entering the council chambers.

[91] Over the weekend, Alderwoman Emma Mitts gave conflicting accounts of the incident to the Chicago City Council's Black Caucus, Mayor Johnson, and her pastor.

"[90] The video also showed Black Caucus Chair Stephanie Coleman "walking by the incident without seeming to notice or feel the need to intervene.

[105] Only six days later Biss dropped him from the ticket after his ally Brad Schneider rescinded his endorsement due to Ramirez-Rosa's support of the BDS Movement,[106] which seeks to impose comprehensive boycotts of Israel until it ends its human rights violations against the Palestinians.

Ramirez-Rosa withdrew on January 9, 2018, and endorsed Jesus "Chuy" Garcia that same day, citing his desire to not split the progressive vote in the Democratic primary.