"Sledgehammer" is a song recorded by American girl group Fifth Harmony. It was written by Jonas Jeberg, Meghan Trainor and Sean Douglas, and was produced by both Jeberg and Harvey Mason, Jr.. It was released on October 28, 2014 as the second single from their debut studio album Reflection (2015). It is a synthpop and electronic dance song about strong feelings for someone that are hard to ignore.

The song peaked at number 40 on the US Billboard Hot 100, making it their first top 40 entry. It also appeared on the US Mainstream Top 40 and Adult Pop Songs charts at numbers 21 and 36 respectively. The song was certified platinum by the Recording Industry Association of America on June 26, 2015. In Canada, it reached a peak of number 63 on the Canadian Hot 100.

An accompanying music video for the song, choreographed and directed by Fatima Robinson, was released on the band's Vevo page. They first performed the song live at the 2014 MTV Europe Music Awards pre-show and would make later appearances on Good Morning America, Access Hollywood Live, The Talk, the Today Show and The Ellen DeGeneres Show.