The album received positive reviews from music critics, with some labeling it the best metal album of 2007. Blabbermouth.net reviewer Don Kaye awarded the album a 9.5 out of 10, saying "The Blackening" is "one of the purest, finest, most powerful expressions of modern heavy metal released" and compared it to the 1986 Metallica album "Master of Puppets", while Allmusic editor Thom Jurek described the album as "an over the top rage and pummelfest with all the qualities that earned the group its enormous fan base by touring and recording", praising the songs "Beautiful Mourning", "Halo", and "Now I Lay Thee Down". "Rolling Stone" reviewer Andy Greene, however, responded negatively as he was displeased with the songs running over ten minutes.