"Let It Happen" is a song by the Australian rock band Tame Impala, released as the lead single from their third studio album Currents (2015) on 11 March 2015. The song centers on accepting personal transition, and was worked on in various locations around the world. The song runs at nearly eight minutes long, and its second half contains a section of the song repeating akin to a scratched Compact Disc, and stripped-down autotuned lyrics consisting of various lines spoken by Parker in live shows. The song peaked at number 29 on the Belgian Flanders singles chart, number 84 on the ARIA Singles Chart and number 152 on the French Singles Chart. In the United States, the song charted at number 28 on Billboard's Adult Alternative Songs chart. "Let It Happen" appeared on many critics' year-end lists of the best songs of 2015. A music video for the song was uploaded on 17 August 2015 to the group's Vevo channel on YouTube.

"Let It Happen" is about "finding yourself always in this world of chaos and all this stuff going on around you and always shutting it out because you don't want to be part of it. But at some point, you realize it takes more energy to shut it out than it does to let it happen and be a part of 'it'." The theme of the album Currents is personal transition, and "Let It Happen" was sequenced as the album's opening song to exemplify acceptance.

Parker detailed the song's globetrotting development in an interview with Under the Radar in 2015:

"Let It Happen" is a psychedelic pop, disco and synthpop song. At one point, the song begins to skip, reminiscent of a skipping compact disc. Producer Kevin Parker included this as an extension of his fascination with glitches in playback. Nearing the song's conclusion, Parker begins singing wordless melodies through a keyboard sampler. He intended to write lyrics for the section, which he dubbed the "speaking in tongues version," but found that it lacked the "groove" of its original incarnation. In keeping with the song's title and subject matter, he left the gibberish in the final track.

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