Born near Albuquerque, New Mexico, the producer born Henry Agincourt Allen studied classical guitar at conservatory before delving into computer-based music production. Inspired by artists like Air, Röyksopp, Black Moth Super Rainbow, Tobacco, and Philip Glass, he crafted beats and found samples across genres. His earliest studio experience came courtesy of Diplo, who brought Allen into his studio as an apprentice and helper. The relationship would eventually bear fruit, with one of King Henry's first hits arriving in 2016 with Major Lazer's Justin Bieber-led "Cold Water." He would go on to work with Beyoncé (her Grammy-nominated "All Night") and the Weeknd ("Nothing Without You"), as well as artists like Charli XCX, Sting, Mark Ronson, and Desiigner.
In 2016, King Henry signed with Black Butter Records for the release of his debut EP, Don't Stay Away. The four-song set featured vocals by NAATIONS, Semma, Emmi, and Bloodboy. The next year, Henry issued the singles "Destiny" with Ry X and "Moment" with Rhye, both of which were later rolled into his second EP, For You. Playing his first-ever live shows at the end of that year, Henry spent 2018 alternately co-writing and producing tracks for Diplo, LANY, and Nina Nesbitt, while releasing his own singles, "Bad for Me" with Elle Watson and "What About Me," the latter of which was the first to feature solely his own vocals. He returned in 2019 with another solo track, "Let You Know." ~ Neil Z. Yeung, Rovi