"Let You Know" is a song by Australian electronic musician Flume, co-written by and featuring singer Hannah Reid of the English indie pop band London Grammar.

"[1] Reid further revealed that the pair had wanted to collaborate "for years" but had been unable to due to their busy schedules, and added that working with the producer was "an honour because he pushes the boundaries of electronic music like nobody else.

Bella Bagshaw of Dancing Astronaut called the song "otherworldly" and highlighted Reid's voice's "swift, almost spectral presence, bolstering the otherworldly, journey-oriented through line of Flume's resounding revamp,"[3] while Sydney Gore of Highsnobiety described the single as a "cosmic collaboration" and "emotionally explosive.

[8] This announcement also previewed the visual for the music, created by Australian graphic designer and long time Flume collaborator Jonathan Zawada.

On 11 June 2019, the track was announced alongside Flume's late 2019 European tour schedule.