"Let's Get Loud" is a song by American singer Jennifer Lopez for her debut studio album, On the 6 (1999). Originally written by the song's co-writer Gloria Estefan for herself, she felt as if the song was too similar to her previous material and passed it onto Lopez. Estefan, who co-wrote the song alongside Kike Santander, stated that Lopez would have "more fun with it" and would put "a new spin" on it. "Let's Get Loud" is sometimes regarded as Lopez's signature song.Estefan eventually released her own version of the song in 2011 as a bonus track on the deluxe Target edition of her album Miss Little Havana.

"Let's Get Loud" charted worldwide, reaching the top ten in five European countries, including number one in Hungary. Although not released in the United States, it charted on the US Billboard Hot Dance Club Songs. The song received positive critical response and at the 43rd Annual Grammy Awards in 2001, Lopez earned her second consecutive nomination for the Grammy Award for Best Dance Recording. An accompanying music video directed by Jeffrey Doe was filmed live at the 1999 FIFA Women's World Cup.