On September 4, 2013, Yuna released the cover artwork for Nocturnal, which depicts her in a floral foreground setting. The official track listing for the album was confirmed by ARTISTdirect on 13 September. On 25 October, the album was made available for streaming in full before it was released.
"Rescue" was released as Nocturnal's lead single on 27 August 2013. It garnered a positive review from MTV Hive, who described the song as a "kick-yourself-in-the-ass ray of sunshine". On 24 September, an official lyric video for the single was released, in which fans were asked to submit Polaroid images with the song's lyrics written beneath them.
Upon release, Nocturnal received rave reviews from contemporary music critics. Matt Collar of AllMusic rated the album four out of five stars, stating that it delivers a "delicate girl power vibe", while comparing Yuna's vocals to those of Sixpence None the Richer's Leigh Nash and English recording artist Ellie Goulding.The Boston Globe's Ken Capobianco gave the album a positive review, noting that it "fleshes out her [Yuna's] acoustic soul while moving toward dance territory".MTV Iggy's Laura Studarus described the album as a guide towards a twinking blend of different genres.