The festival was held from July 29 to August 1.
In addition to the 19 arrests, 7 people were given citations/tickets.
Chicago said that 102 people were transported for medical reasons.
City of Chicago officials said that from a public safety perspective, the event was a success.
"There was a lot of planning and fortunately we had a lot of good people around the table," said Rich Guidice, Executive Director of the Office of Emergency Management and Communications. "Overall, we would consider it a success on pretty much all levels."
In 2019, 31 people were arrested, 12 cited, and 116 transported for medical reasons. In 2018, 12 people were arrested, 34 cited, and 160 transported for medical reasons.
There have been concerns that Lollapalooza attendees would spread COVID, and Gov. JB Pritzker, who had planned to attend, skipped the event out of "an abundance of caution." Chicago Mayor Lori Lightfoot did attend some performances. She said that 90% of all attendees were vaccination.