"Waking Up in Vegas" is a song by American singer Katy Perry, released as the fourth and final single from her second studio album, One of the Boys (2008).

The song received positive reviews from music critics, who complimented its catchiness, and attained commercial success, reaching the top ten in eight countries.

The music video was directed by Joseph Kahn and it features Perry and actor Joel David Moore in Vegas partying and gambling.

The song is a playable track in the 2015 video game Guitar Hero Live and was added to Rock Band 4 in March 2022 as DLC.

According to A&R Chris Anokute, "Waking Up in Vegas" played a significant role in initiating Perry's pivotal move to Capitol Records.

[4] In an interview with HitQuarters, one of the songwriters of the song, Andreas Carlsson, claimed that he worked together with Perry and Desmond Child to write "Waking Up in Vegas".

We went and bought a wedding dress and a suit at a thrift store, and scanned the pictures and the certificate to my family members, my manager at the time [and] totally freaked the shit out of them.

[6] "Waking Up in Vegas" was eventually picked as the album's fourth and final single, being sent to US radio stations on April 21, 2009.

"Waking Up in Vegas" also went on to become Perry's second number one hit on Mainstream Top 40, matching the airplay success of "Hot n Cold".

"[15] Digital Spy gave "Waking Up in Vegas" 3/5 stars, calling the song "a giddy pop-rock romp featuring an ace sing-along chorus.

Subsequent scenes show the couple playing various casino games and parlaying their winnings into millions, defeating poker legend Daniel Negreanu, and being welcomed into the Palms Hotel by owners Gavin and George J. Maloof Jr. As the winning streak continues, Perry and Moore enjoy a lavish lifestyle, racing through the streets of Las Vegas in his-and-hers Lamborghini Murciélagos.

At the height of the streak, they are dressed in show costumes while riding in chariots down Fremont Street, accompanied by a fire-breather and an elephant.

They lose all their winnings except a single quarter and are ejected from their hotel suite (which Penn and Teller reclaim, even performing a card trick before slamming the door on the couple).

She was also a guest on Ant & Dec's Saturday Night Takeaway in March 2009 where she performed "Waking Up in Vegas" instead of her then-current single, "Thinking of You", which had been released that month.

During the Vegas stop of Witness: The Tour, Perry sang an acoustic snippet of the song for fans, before performing "Thinking of You".