The song was released for digital download and streaming as a single by Sony Music Latin and Head Concussion Records on September 8, 2021.

A primarily Spanish language R&B-infused reggaeton and dancehall song, it reminisces on a past relationship that the singers want back.

The track received widely positive reviews from music critics, who complimented its Caribbean beats and the singers' exchange of verses.

[2][3] "Nostálgico" marks Brown's fourth collaboration on a Spanish language song, following "Algo Me Gusta de Ti" (2012), "Control" (2014) and "Just As I Am" (2017).

[4] The song was released for digital download and streaming by Sony Music Latin and Head Concussion Records on September 8, 2021, as a single.

In his review for DancehallMag, Donovan Watkis labeled the song "a late summer banger",[10] while an author of HipHop-N-More called it "vibey".

[11] Lucas Villa from mitú named Alejandro and Brown a "twinkling duet" and described them as "magical, sexy, and irresistible".

[2] In 2022, Ernesto Lechner from Rolling Stone ranked the track as Alejandro's 41st-best song, saying it "echoes the profound imprint of Jamaica in its DNA", and praised "the exchange of verses" between the singers as "flawless".

[15] "Nostálgico" debuted at number 14 on the US Billboard Hot Latin Songs chart on September 25, 2021,[16] becoming Rvssian's 5th entry, Alejandro's 24th, and Brown's 4th.

It subsequently peaked at number three on the chart for two consecutive weeks, becoming Rvssian's first top 10 hit in the country, Alejandro's twelfth, and Brown's second.