"Let's Go Crazy" is a 1984 song by Prince and The Revolution, from the album Purple Rain. It is the opening track on both the album and the film Purple Rain. "Let's Go Crazy" was one of Prince's most popular songs, and was a staple for concert performances, often segueing into other hits. When released as a single, the song became Prince's second number-one hit on the Billboard Hot 100, and also topped the two component charts, the Hot R&B/Hip-Hop Songs[4] and Hot Dance Club Play charts,[5] as well as becoming a UK Top 10 hit. The B-side was the lyrically controversial "Erotic City". In the UK, the song was released as a double A-side with "Take Me with U".

Common to much of Prince's writing, the song is thought to be exhortation to follow Christian ethics, with the "De-elevator" of the lyrics being a metaphor for the Devil.[6] The extended "Special Dance Mix" of the song was performed in a slightly edited version in the film Purple Rain. It contains a longer instrumental section in the middle that includes a chugging guitar riff, an atonal piano solo and some muddled samples of the spoken word intro. This version was originally going to be used on the album but when "Take Me With U" was added to the track list, it was edited down to its current length.

Cash Box called the song "one of the finest fusions of jump rock and synth pump."[7]

Following Prince's death, the song re-charted on the Billboard Hot 100 singles chart at number 39 and rose to number 25 by the week of May 14, 2016. As of April 30, 2016, it has sold 964,403 digital copies in the United States.[8]

In 2013, British rock band The Darkness performed the song at the 44th Annual Rock Music Awards.