Chicago Fire Department spokesman Larry Langford said the transported man experienced cardiac arrest and was taken to a hospital from a small hangar at Midway, where private planes land.
Juice WRLD was named top new artist at the 2019 Billboard Music Awards in May.
Born and raised in Chicago, he had enjoyed a rapid ascension since he first began posting his songs to SoundCloud as a teenager in 2015, working in a style that blended elements of emo and rock with hip-hop.
His independently-released 2017 track Lucid Dreams proved to be a career-maker, rising steadily until an official single release in 2018 broke him on to the pop charts, where the song would peak at No. 2.
Signing to Interscope Records in early 2018, Juice released his debut album, Goodbye & Good Riddance, almost immediately after, which was certified platinum before the end of the year, and contained yet another No. 2 single in All Girls Are the Same.
His busy year continued with a summer in memoriam EP dedicated to late fellow SoundCloud rappers XXXTentacion and Lil Peep; a collaborative album with Future, Wrld on Drugs, which reached No. 2 on the album chart in October; and an original song on the soundtrack for the film Spider-Man: Into the Spider-Verse.
Juice released his second album, Death Race for Love, earlier this year. It was his first effort to reach No. 1 on the album chart. Also this year, he toured Europe with Nicki Minaj on a co-headlining bill.