Carey's vocal range spans more than three octaves; her delivery is predominately breathy and in a low register, with whistle notes in the song's introduction and ending.

Music critics considered "Can't Let Go" a vocal showcase for Carey but gave the composition mixed reviews.

Elsewhere, the song peaked within the top ten on sales and airplay charts in Canada and at number twenty in the United Kingdom.

She performed "Can't Let Go" on several American and British television programs such as MTV Unplugged, Saturday Night Live, and Top of the Pops.

After its release in June 1990,[1] American singer Mariah Carey's eponymous debut album sold over seven million copies and four of its singles reached number one on the US Billboard Hot 100 chart.

[2] She resumed work with Walter Afanasieff in late 1990 for her second album Emotions (1991); he had produced the Mariah Carey single "Love Takes Time" earlier that year.

[6] Sociology professor Thomas J. Scheff said the lyrics "My world is gone" and "But still you remain on my mind" show that the relationship in the song is defined by how a lover thinks they lack a future without the other who has moved on.

[20] "Can't Let Go" opens with a minute of synthesizer and guitar instrumentation interspersed with faint notes from Carey in the whistle register.

[18] Chan thought this conjured "a sensation of space and distance"[18] and biographer Chris Nickson remarked it resembled a hymn.

Music professor Richard Rischar identified this as an example of the unique timbre patterns typically heard in ballads by Black artists.

[14] Assisted by Bruce Calder, Craig Silvey, Manny LaCarrubba, M. T. Silvia, and Lolly Grodner, Dana Jon Chappelle engineered "Can't Let Go" at Skywalker Sound in Marin County, California; The Plant Recording Studios in Sausalito, California; and Right Track Recording in New York City.

After Afanasieff and Carey produced the song, Chappelle conducted mixing at Right Track Recording and Bob Ludwig mastered it at New York City's Masterdisk.

Tampa Tribune writer Wayne Garcia thought her breathy delivery helped make "Can't Let Go" worthwhile.

[36] Randy Clark and Bryan DeVaney from Cash Box commented: "Her voice still has that crystal-clear sound that has hypnotized listeners of all sorts.

[42] According to Entertainment Weekly's Whitney Pastorek, "something in the structure creates these places where it could jump off and go in a different direction, sprout another tune, but then it zigs where it seems like it should zag".

[46] On the comparative Top 100 Pop Singles chart published by Cash Box, "Can't Let Go" became Carey's sixth consecutive number one song.

[50] The Recording Industry Association of America awarded "Can't Let Go" a gold certification in 2022, which denotes 500,000 units based on digital downloads and on-demand streams.

[55][56] On the pan-European sales chart compiled by Music & Media, "Can't Let Go" achieved a top ranking of sixty-nine.