"I am running for the U.S. Senate because the people of Illinois deserve an honest, independent broker and a bold advocate in Congress who is a problem-solver and not just a politician," Jackson said.
Jackson is the only black Democrat so far seeking the seat that has been held by three of the nation's four black senators.
But Jackson already has political baggage because of her Blagojevich ties. She worked as his spokeswoman during his first term, when federal prosecutors were investigating his administration's hiring practices.
"Those were not my decisions," said Jackson, who left the administration to join the Chicago Urban League in October 2006.
Jackson's Chicago roots are deep. Jackson serves as a director on the boards of the Field Museum, the Chicago Symphony Orchestra, Northwestern University, the Metropolitan Planning council, the Chicagoland Chamber of Commerce and on Chicago's 2016 Olympics committee.
She is a graduate of Northwestern University.
Jackson will have some high-profile help with her campaign. She's retained David Wilhelm, a former Democratic National Committee Chairman who helped engineer President Bill Clinton's winning campaign, as a special adviser.
Incumbent Sen. Roland Burris isn't seeking a full term after having been appointed by Blagojevich. Burris was appointed by Blagojevich before the then-governor was removed from office by lawmakers after his arrest on federal corruption charges.
Jackson will be part of a February Democratic primary that includes first-term Illinois Treasurer Alexi Giannoulias, former Chicago Inspector General David Hoffman and Chicago attorney Jacob Meister.