Witness is the fourth studio album by American singer Katy Perry, released on June 9, 2017. The album's lead single, Chained To The Rhythm (feat. Skip Marley), was released on February 10, 2017. A second song, titled Bon Appétit (feat. Migos), followed on April 28, 2017. - Witness is the fourth studio album by American singer Katy Perry, released on June 9, 2017. The album's lead single, Chained To The Rhythm (feat. Skip Marley), was released on February 10, 2017. A second song, titled Bon Appétit (feat. Migos), followed on April 28, 2017.