Club wrote that Junk is "easily M83's most challenging, best album to date", praising the tracks for being "unassumingly gorgeous and maudlin, with jarring unpredictability" and Gonzalez for "coaxing jaw-droppingly stunning performances" from his special guests like Sundfør, Steve Vai and Beck, concluding that: "Junk can be a difficult listen at points, but Gonzalez has been given time and attracted ample collaborators due to the sheer good will of being a musician who cares about music.

"[14] In The New York Times, Ben Ratliff wrote that Junk "expands somewhat on the strengths of Hurry Up, balancing Italo-disco chill-out atmospheres and calibrated buildups and releases.

"[16] Harley Brown of Spin found some "poignant moments" ("Do It, Try It", "Solitude") on the album, but felt the rest of the homages to 80s cheese were "so outlandish they sound almost ironic," and that Gonzalez wasn't putting much effort into crafting his own "nostalgic fantasies".

[21] Greg Kot of the Chicago Tribune commended the middle portion ("Solitude", "Laser Gun", Road Blaster") for being able to "merge [the album's] junk-pop sensibility with inventive arrangements" but found it "decidedly mixed" overall, concluding that: "M83 has rarely made music that sounds emotionally hollow, but Junk provides an unfortunate exception.

"[1] Suzy Exposito of Rolling Stone gave praise to the featured artists throughout the track list, singling out Mai Lan's performance on "Laser Gun" and "Atlantique Sud" for putting a "timeless, ghostly vocal sheen" on a record that "leans too heavily on the quirks from the past, rife with the least flattering odds and ends of a time long gone.

The website's writer Ryan Leas called it "the sound of youth's forgotten detritus, filtered through the wrong drugs, playing out like a frantic-then-hazy Day-Glo plot twist to the neon romanticism of Hurry Up, We're Dreaming."