Guestroom Records on Frankfort Avenue hosted Harlow for an in-store appearance.
Attendees were allowed into the store with the purchase of a limited edition autographed CD of Harlow's "Come Home the Kids Miss You" album.
Evan Olinger is a big fan of Jack Harlow - showing his appreciation for the Louisville rapper through his art - a colored pencil drawing that took him 10 hours.
The line wrapped around the store and lasted several blocks as some people waited more than 24 hours to get a chance to meet Harlow.
Harlow arrived in a black SUV accompanied by several security guards and made his way straight to the store, through the screaming crowd.
Prior to his signing, Harlow spent the weekend in Louisville - hosting a Derby Eve party at the 21c Museum Hotel and calling "riders up" for the 148th race of the Kentucky Derby.
However, Sunday was a special day for the fans.
"I think we are all so proud. We are proud of Louisville, we're proud of Jack, we're proud of each other -
- it's just a good day to be in Louisville," said store manager Lisa Foster.