In August 2018, it was announced that Harlow had signed to DJ Drama and Don Cannon's Atlantic Records imprint, Generation Now. He also released a video for his single "Sundown" on the day of the announcement. On August 17, Harlow released his major label debut mixtape, Loose. The album featured guest verses from CyHi the Prynce, K Camp, 2forwOyNE, and Taylor. In September 2018, he performed at the Genius IQ/BBQ event. In November 2018, Harlow embarked on a North American tour in support of Loose which ended in December. That month, he also released a music video for the song, "PickYourPhoneUp", featuring K Camp. Loose was nominated for Best Mixtape at the 2019 BET Hip Hop Awards. On August 21, 2019, Harlow released the single "Thru the Night" featuring fellow Louisville native Bryson Tiller. He then released a 12-track mixtape named Confetti, with features from the previously mentioned Bryson Tiller, as well as 2forwOyNE and EST Gee and launched his US tour, which started in October of the same year.