The accompanying music video for the song was uploaded onto MLD Entertainment's YouTube channel simultaneously with the single's release.

Cara Emmeline Garcia of GMA Network stated the song "shows the members' charms and confidence with its saxophone hook and upbeat.

[5] Following the release of "Starry Night", MLD Entertainment announced on October 19 2020 that the group would be making their comeback in their fourth anniversary in November 2020.

[7] The song was officially released on November 17, 2020 by MLD Entertainment and distributed by Sony Music as the group's third single album.

"[15] In South Korea, "Ready or Not" debuted and peaked in the Gaon Download Chart at number eighty-one on the week of November 21, 2020.

[18] The music video for "Ready or Not" was uploaded to MLD Entertainment's official YouTube channel on November 17, 2020, in conjunction with the release of the single.

[15] Seoul Beats described the video as "simple" and "it forgoes a fun narrative and offbeat concept in an attempt to step away from the group's quirkier image.