Timothy Evans, the presiding judge of the Cook County chief judge, told county commissioners weeks ago that Obama would serve in November, but would not say when.
Obama took a private elevator with his security to the room, where he shook almost every hand.
Obama departed his home in the Kenwood neighborhood of the city Wednesday morning with a motorcade of black SUVs in tow.
Thomas Pearson, who took the video and called the experience of shaking hands with Obama "the best thing I experienced in my entire life", said he wasn't going to show up for jury duty until his mother texted him that Obama would be there. "No one is excused", Evans said after Obama's departure. The official, who is not authorized to speak about the former president's jury duty, spoke on condition of anonymity. When he arrived there was a feeding frenzy as crowds of people inside the courthouse took photos and videos of the former president.
Theoretically, every USA citizen over the age of 18 could be called for jury duty.
Bush reported for jury duty in Dallas, Texas in 2015.
Had he been selected the 44th president would also be in line to receive the $17.20-a-day (£13.12) that jurors are paid for carrying out the civic duty.
While the Obamas now live in Washington, the former president and first lady Michelle Obama maintain a home in Chicago, the city where he got his political start. In 2004, Oprah Winfrey was on a Chicago jury that convicted a man of murder.