[3] Mitchell began his career as a community organizer, working with churches on the south side of Chicago and is an advisor to many reform-minded political leaders.

In 2009, Mitchell drafted legislation that became the Urban Weatherization Initiative, a $425 million program designed to put people to work weatherproofing houses in Chicago.

He was a senior advisor to Cook County President Toni Preckwinkle from May 2011 to November 2011, serving as Director of Outreach and External Relations.

Preckwinkle credits Mitchell with keeping the Todd Stroger sales tax repeal from unravelling in the Cook County budgeting process.

He worked as a senior vice president at The Strategy Group from 2014 to 2017, executing strategic communications plans for Democratic candidates across the United States.

[12] On Wednesday, October 30, 2013, Mitchell told Dartesia Pitts on CAN TV's Political Forum that he views "education as the key to opportunity, as a ladder out of poverty, as the thing that got me to the place where I am".

In a speech from the Illinois House floor on May 14, 2015, he opposed an initiative to create local employment empowerment zones, stating "without unions, we wouldn't have an African American middle class.

[31] He also co-sponsored legislation which became law to expand access to SNAP benefits for families that include an elderly, disabled, or blind person.

The state budget, passed by the legislature and signed into law by Governor Bruce Rauner, avoided property tax increases - a major selling point for Mitchell.

[citation needed] In the legislature, Mitchell has championed measures to preserve the environment and move Illinois towards a clean energy economy.

[33] Mitchell was a vocal supporter of a stronger Renewable Portfolio Standard, which steered a larger share of state investments to sustainable energy sources.

[37] This legislation expands access to the program for thousands of working families, particularly single parents and is a bill that Mitchell has carried since he was sworn into the General Assembly.

[38] On November 17, 2015, Mitchell expressed his support for expanded child-care in an interview with Paul Lisnek, saying "I've got child care providers in my district who are shutting down.

[37] In March 2017, Mitchell introduced HB 3595, a bill that would create tax credits to help working parents cover child care expenses.

[41] Mitchell is an ardent supporter of criminal justice reform, recognizing the disproportionate effect current drug laws have on minority communities.

[citation needed] In July 2018, Mitchell was named Interim Executive Director of the Democratic Party of Illinois, the first African American serve in the role.

[43]  As Executive Director, Mitchell traveled to every corner of the state, listening to and soliciting feedback from voters on how they’d like to see the party grow and continue its record of electing Democrats in Illinois.

In concert with J.B. Pritzker's campaign for Governor, the Party launched a $1 million voter registration program; executed a massive vote-by-mail program, targeting nearly two million eligible voters to ensure broader access and engagement during the traditional “drop-off” (non-presidential) midterm election year; and increased data sharing among campaigns from the top of the ticket to the bottom, giving down-ballot races access to additional data from which they could produce more sophisticated targeting and better-coordinated field operations.

Mitchell, in concert with the sponsors and caucuses of color, not only worked to ensure that HB 1438 would generate much needed revenue, but also guaranteed that the Act was rooted in equality and justice.

The Illinois bill is noted for wrapping in "significant criminal justice reform"[49] through a combination of clemency and expungement for a half million individuals that have been convicted of minor offenses.

Industry experts applaud actions taken by the Illinois legislature for “marrying increased opportunity, increased access [to] points of sale, while at the same time really giving the current operators, the current infrastructure the opportunity to be first to market.”[51] Other components of the law will expand mental health and addiction recovery services and reinvest in economic development, violence prevention, youth services, re-entry programs, and legal aid.

[52] Also during the 2019 legislative session, Mitchell spearheaded efforts that led to the passage of “Rebuild Illinois”, the first-of-its-kind $45B Capital Construction Program.