Garcia defeated two competitors on Tuesday's ballot. He will face Republican financial adviser and first-time candidate Mark Lorch of Riverside in November.
Garcia led community activist Sol Flores and longtime Chicago police officer Richard Gonzalez in name recognition, endorsements and fundraising. In 2015, he forced incumbent Chicago Mayor Rahm Emanuel into an unprecedented runoff election.
Key issues in the race were immigration, affordable housing, education and crime. The heavily Hispanic and Democratic district covers Mexican, Puerto Rican and Central American swaths of Chicago and several suburbs.