Kelly's campaign focused on gun control, and she drew the financial support of New York City Mayor Michael Bloomberg's Super Political Action Committee.
At 8 p.m., Kelly had won an overwhelming majority in Chicago's south suburbs. With 185 of 263 precincts reporting, she had 79 percent of the vote.
Kelly had an even greater lead in Chicago. With 135 out or 170 precincts' votes tallied, Kelly had almost 92 percent of the vote with 9,753.
In a distant second was Republican candidate Paul McKinley with almost 5 percent of the vote in Chicago and about 14 percent in the suburbs.
"We not only won an election, we took on the NRA, we gave a voice to the voiceless, and we put our communities on a brand new path to a brighter day," Kelly's prepared remarks said. "Yes, we've seen some tough times and some setbacks. I know for some of you, your faith in your leaders is a little shaken."
The 2nd Congressional seat was vacated by Jackson Jr. soon after he won reelection in November. Jackson later pleaded guilty to misspending campaign funds, along with wife and former Ald. Sandi Jackson (7th).
Mayor Rahm Emanuel appointed Natashia Holmes to replace Sandi Jackson.
Kelly moved to an easy victory in February as the party frontrunner for the mostly Democratic district.