“Buttons” was released as the 4th single from PCD. This song is a pop, R&B, hip-hop song with a Middle-Eastern sound. It’s about Nicole wanting her partner to take her clothes off. The song managed to peak at number three on the Billboard Hot 100. It reached the top-five in countries such as Australia, Germany, and the United Kingdom and reached number-one in Austria and in New Zealand.

The single has sold two million copies digitally in the US, which made The Pussycat Dolls become the first female group in digital history to have three singles pass the two million mark there. A music video was released for the single that featured Snoop Dogg, and has been Vevo-certified.