It was released as the EP's first single on January 13, 2025, by Starship Entertainment.

[5] "Rebel Heart" was written by Nietzsche, composed by Emily Harbakk, Ryan S. Jhun, Thomas Gustafsson, Jimmy Jansson, Maia Wright, Jack Brady, and Jordan Roman, and arranged by Ryan S. Jhun, Gucci Caliente, and The Wavys.

[19] The song also debuted at number 21 on the RIAS Official Singapore Regional Chart in the chart issue dated January 10–16, 2025,[20] ascending to number eight in the following week.

[23] In United States, "Rebel Heart" debuted at number six on the Billboard World Digital Song Sales in the chart issue dated January 25, 2025.

[28] Ive performed the song on four music programs in the first week of promotion: Mnet's M Countdown on January 16,[29] KBS's Music Bank on January 17,[30] MBC's Show!