Dowell was elected alderman for the 3rd ward in 2007, unseating incumbent Dorothy Tillman. She has subsequently been reelected in 2011, 2015, and 2019. Dowell introduced the amendment to the Vacant Property that was passed by the Chicago City Council on July 28, 2011, holding banks responsible for maintaining foreclosed properties in neighborhoods across Chicago. Dowell commented on the issue, saying: "The foreclosure process sometimes takes a year or 18 months, two years for them to actually foreclose on the property and sometimes certain banks let those properties sit vacant....They can become haven for gang bangers and drug dealers; there is also the potential for fire hazards.....When vacant buildings are left to deteriorate, local property values tumble and criminality gains an entry into the neighborhood.....The landmark piece of legislation passed today will hold banks responsible for the upkeep of vacant properties, keeping them secure and keeping neighborhoods intact." Dowell also stated that: "This legislation goes a long way to keep our neighborhoods vibrant and soften the negative impact the housing foreclosure process has had on the city." Dowell was the recipient of the Independent Voters of Illinois' Best Aldermanic Voting Record for 2010, presented by the Independent Voters of Illinois-Independent Precinct Organization, a not-for-profit, multi-partisan, independent political organization that has been in existence since 1944 dedicated to good government activism. Dowell along with Alderman Bob Fioretti and Alderman Joe Moore, was given IVI-IPO's Best Aldermanic Voting Award. Upon receiving the award Dowell stated: "I am thankful for the IVI-IPO recognition of my work in the City Council and my commitment to good government and participatory democracy. These are values I hold most dear and I'm proud to be associated with an organization like IVO-IPO that has been fighting the fight for social justice for over 60 years." In 2018, J.B. Pritzker appointed Dowell a member of the gubernatorial transition's Job Creation and Economic Opportunity Committee. In the runoff of the 2019 Chicago mayoral election, Dowell endorsed Toni Preckwinkle. On May 17, three days prior to her inauguration, Lori Lightfoot announced that she would be naming Dowell to be the City Council's budget chairman.
