Jamee-Beth Livingston of Breakaway Daily said the song brings "a deeper level of honesty and realness" in their songwriting.

[8] Tim Sendra of AllMusic was positive and said that "Dark Side" "has a loose-limbed bounce that's missing from the pro tracks, the disco throwback".

[10] Katy Amjs of Music Is The Home For You Pain said she was surprised by the disco rhythm and commented: "Unlike its title indicates, the track is fast paced from the first beat and maintains its energy throughout".

[11] Emery Columna of Maaf Box said that "Dark Side" is the key that opens the traditional rock door that held the R5 within the predictable.

He also said: "[the song] is a clue to where R5 can go musically to break the evil spell some [critics] have unfairly cast upon this groovy band".