The song was written by a sextet of Swedish songwriters and producers: Emanuel Abrahamsson, Linnea Södahl, Iman Hultén, Markus Sepehrmanesh, Christoph Bauss and Fridolin Walcher. It came together at a writing camp in Stockholm. Larsson explained to Genius
"A writing camp works like this: A lot of people - producers, writers, top liners—they come in. Let's say 25 people, 30 people. We have a studio complex in Stockholm, so we've got a lot of studios. We just put a little group in every room. That's the way we do it.
By the end of the week, we all play the songs for each other. 'Lush Life' was really the only song that stood out that I was like, 'Whoa. What is this?' It just had a really nice vibe to it, and I love it so much. We were approaching summer, and it's a very good summer song."