Feldt's early releases included 2014's "Bloesem" with De Hofnar and "Hot Skin" with Kav Verhouzer on the Dutch label Spinnin' Records. After a series of live shows in Europe, which he built over time to contain mostly his own productions, he toured North America for the first time in early 2015. "Midnight Hearts" with the Him and featuring ANG13 followed soon after, and that spring, Feldt signed with Universal Music for the worldwide release of his song "Show Me Love" featuring English vocalist Kimberly Anne. It charted throughout Western Europe, hitting the Top Five in the U.K., as well as landing on the dance and streaming charts in the U.S. By the end of 2015, he'd performed on five continents.
The following summer, Feldt had a hit at home with "Summer on You," a collaboration with Lucas Steve and Wulf. That same year, he issued his first EP, Been a While, which featured guests like Dante Klein, Milow, Lulleaux, and Bright Sparks. "Runaways," with Deepend featuring Teemu, followed in late 2016 and charted in Europe, later spawning a remix EP. The next year, Feldt released his debut LP, Sunrise, which featured the singles "Yes" with Akon, "Fade Away" with Lush Simon and Inna, and "Be My Lover" with Alex Schulz. An album of remixes, After the Sunset, arrived in 2018, as did the single "Heaven (Don't Have a Name)," which featured vocals from actor Jeremy Renner.
Spring 2019 saw Feldt issue the singles "One Day" featuring ROZES and "Magnets" featuring Sophie Simmons. The EP Magnets appeared in May 2019 and included the song "Post Malone" featuring singer Rani. The track landed at number four on the Billboard Hot Dance/Electric Songs chart. In May 2020, Feldt launched his own Heartfeldt Records with the release of "Hold Me Close" featuring Ella Henderson. A second song from the label, "Far Away from Home" with Vize and Leony, followed a month later. Feldt's third EP, Home Sweet Home, arrived in November 2020 and included guest spots by Alma, Digital Farm Animals, Karma Child, and others. In 2021, he paired with Kesha on the non-album track "Stronger." Other releases that year included "Pick Me Up" with Sam Fischer, "Call on Me" featuring Georgia Ku, and charting Dutch hit "Follow Me" with Rita Ora. The collaborations continued in 2022 with the Salem Ilese-assisted "Hate Me" and "Late Night Feels" featuring Monsta X. ~ Marcy Donelson, Rovi