Daydream received critical acclaim, with reviewers praising the album's production, its sonic quality, and Carey's musical progression.

[4] While Columbia allowed Carey more leniency with the music she recorded, they became hesitant when she featured Ol' Dirty Bastard in the remix for "Fantasy".

"[5] While Carey's new musical direction caused tension between her and Columbia, it began to severely strain her relationship with her husband at the time, Tommy Mottola.

Since the time of Carey's debut, Mottola had controlled nearly every aspect of her career, keeping her sound carefully regulated and insisting that she continue recording middle-of-the-road pop music, despite her interest in hip hop.

[6] During the recording of Daydream, Carey also worked on the alternative rock album Someone's Ugly Daughter by the band Chick, contributing writing, production, vocals and art direction.

[20] Returning to her R&B territory, Carey recorded "Long Ago", the second song she wrote alongside Dupri and Seal which contains a strong hip hop background.

[21] According to Chris Nickson, "Melt Away" was as "strong as any slow jam released in the nineties, and one that would find a lot of flavor late at night with dancers.

This was possibly due to the mixed reception Carey's 1993 North American Music Box Tour received three years prior.

[26] They included "Fantasy", "One Sweet Day", "Open Arms", "Always Be My Baby", "Forever" and "Underneath the Stars" as well as hits from her previous studio efforts.

[27] After "Fantasy" was released in September throughout Europe, Carey performed the song on the popular British chart show Top of the Pops, which aired live via satellite on Asian television.

[27] "One Sweet Day" was performed at the 38th Annual Grammy Awards, Princess Diana's memorial service in September 1997, and at Carey's Black Entertainment Television Christmas special in 2001.

[27] During her European promotional tour for the album, Carey performed "Open Arms" on various television programs, including Wetten, dass..?

Stephen Holden of The New York Times wrote that Carey's songwriting had improved dramatically, "becoming more relaxed, sexier, and less reliant on thudding clichés".

"One Sweet Day", "Melt Away", "Always Be My Baby", and "Underneath the Stars" were singled out as highlights, while "Fantasy" featured what Holden described as "some of the most gorgeously spun choral music to be found on a contemporary album".

[48] Los Angeles Times journalist Cheo H. Coker said Daydream boasted material that would silence Carey's critics—especially "Fantasy" and "Underneath the Stars"—and offered "something for everybody while somehow remaining true to her essence".

[44] People magazine deemed it Carey's best album, benefiting from "funkier and mellower" songs and the singer's improved control over her voice, "evincing greater muscularity and agility".

[49] According to Encyclopedia of Popular Music writer Colin Larkin, "some critics questioned whether Daydream was a controlled exercise in vacuous formula writing, with little emotion or heart.

"[43] Reviewing the album for Entertainment Weekly, Ken Tucker preferred the "less dignified tunes"—particularly "Daydream Interlude (Fantasy Sweet Dub Mix)"—over the "monuments to assiduous good taste" in "When I Saw You" and "I Am Free", which he panned as overwrought ballads.

In Erlewine's opinion, the album appealed to both urban R&B and adult contemporary audiences while showing that "Carey continues to perfect her craft, and that she has earned her status as an R&B/pop diva.

In Canada, Daydream peaked at number two on the charts, and was certified seven-times Platinum by the Canadian Recording Industry Association (CRIA).

[63] In Australia, Daydream was certified five-times Platinum by the Australian Recording Industry Association (ARIA), denoting shipments of 350,000 copies.

[71] Pitchfork writer, Jamieson Cox, called the album, specifically "Underneath the Stars", a "tribute to '70s R&B legends like Minnie Riperton, complete with vinyl crackle".

[72] Carey began a "seamless blend of pop and hip-hop" within this album, but eventually went on to be the core of Butterfly, and it served as the foundation for her late-career reinvigoration nearly a decade later.

[82] Andrew Chan, author and editor of Why Mariah Matters (2023), identified Daydream as a cultural moment, recalling that its chart-topping singles “Fantasy”, “One Sweet Day”, and “Always Be My Baby” were virtually inescapable for at least two years following the album's release.

[88] The album features several musical trademarks that would become staples of Carey's work, namely catchy hooks, emotional ballads, powerful vocals, and R&B influences.

[78][88][93] According to Kailyn Hayes of Hilltop Views, the album established "the tone for how a true MC song should sound" by allowing her to assert her independence for the first time in her career, which would only be cemented by its immediate successor Butterfly.

[88] Hayes credited Daydream with inspiring future pop acts such as Taylor Swift, Ariana Grande, and Ed Sheeran to pursue their own collaborations with rappers and hip hop artists.

[94] Journalist Audie Cornish said Daydream's musical direction and success spared Carey from being relegated to "a glitter-laden version" of singer Whitney Houston.

[73] A writer for Slant Magazine reported that Carey had "arguably reached a new apex in her career" with Daydream due to its mainstream, mass pop appeal, and "perfectly balanced" selection of songs.

[93] Cox observed that by preceding the less successful albums Rainbow and Glitter by a few years, Daydream now indicates that Carey's "absolute commercial zenith would soon be in the rear-view mirror".