The album debuted at number eight on the US Billboard 200 chart, selling 63,000 copies in its first week. Upon its release, Wake Up! received positive reviews from most music critics, who complimented its production and the artists' treatment and performance of the material. It would go on to win the 2010 Grammy award for Best R&B album.
Wake Up! follows the releases of John Legend's Evolver (2008) and The Roots's How I Got Over (2010). Legend and The Roots were inspired to record a collaborative album by the 2008 United States presidential election. In an interview for Billboard, Legend explained the album's conception at the time, stating "I was in the middle of campaigning for Barack Obama and feeling inspired by the atmosphere in the country at the time, so I wanted to do something musically that reflected that moment. The original idea was to do some sort of covers EP, but the more I got into it with the Roots, it felt like something that should be heard and marketed on its own". The album's title was inspired by Canadian rock band Arcade Fire's song of the same name.
Wake Up! features mostly covers of songs from the soul music of the 1960s and 1970s, and incorporates musical elements from gospel, rock, reggae, and hip hop. Songs covered for the album include "Wholy Holy" by Marvin Gaye, "Little Ghetto Boy" by Donny Hathaway, "Hard Times" by Baby Huey & the Babysitters and "Hang on in There" by Mike James Kirkland. The lone original song for Wake Up! is the Legend-penned album closer "Shine". A different version of "Shine" was included in the album's deluxe edition and is used during the closing credits of the 2010 film Waiting for "Superman". In an interview for The Guardian, Ahmir "Questlove" Thompson of The Roots said that they intended to cover lesser-known soul songs, stating "I wanted to choose cover songs that were so under the radar, so uniquely interpreted, that it would take you a second to realise that these are cover songs [at all]". Questlove has said that the band's instrumentation for the album is looser than on previous albums, with a jamming and "grass-roots feel".Wake Up! contains lyrical themes concerning social awareness, engagement, and consciousness. The Roots's lead MC Black Thought is featured on few tracks, as the band mostly accompanies Legend's singing with live instrumentation. Other rappers featured on the album include Common, CL Smooth, and Malik Yusef.
Wake Up! received generally positive reviews from music critics. At Metacritic, which assigns a normalized rating out of 100 to reviews from mainstream critics, the album received an average score of 76, based on 22 reviews, which indicates "generally favorable reviews". Sean Fennessey of The Washington Post called it "a surprisingly rugged enterprise" and complimented The Roots' "brawny arrangements of a cleverly curated batch of songs".About.com's Mark Edward Nero commended their "outstanding job" as a backing band and called Wake Up! "a very moving, extremely well-performed and well-produced album".Rolling Stone writer Jody Rosen called it "a brilliantly conceived and executed album" and stated "Legend and the Roots capture the old feeling of protest and uplift while updating the sound". Jeff Vrabel of Paste called it "organic and opulent, with a heart of diamonds and a lush sound to match".The Boston Globe's Julian Benbow noted Legend's range and stated, "The Roots band practically makes sonic photocopies of the originals".Newsday's Glenn Gamboa stated, "Legend's rich soul vocals and The Roots' equally lush soul arrangements succeed in updating these classics subtly, making them fit admirably both in the past and the present". Steve Jones of USA Today stated, "The Roots contemporize them with just enough hip-hop flavor, while the soulful Legend injects them with renewed passion". In his Consumer Guide, Robert Christgau gave the album a three-star honorable mention (); he picked out two of its songs ("Compared to What" and "I Can't Write Left-Handed") and called it "A myth of conscious soul neither the singer nor his attendant rappers can quite put across."
Chicago Tribune writer Greg Kot noted that "Legend sings with more grit than usual, and the Roots crackle with energy", but stated "This well-intentioned collection never surpasses the strong originals from which it draws". Mikael Wood of Spin viewed that "The results don't always play to [Legend]'s melodic strengths; ?uestlove sounds a bit reined-in, too".AllMusic writer Andy Kellman shared a similar sentiment and commented that "There are several instances when the Roots, who are deeply intimate with grit, outshine Legend, whose polished and pride-rich voice occasionally clashes with the material".Chicago Sun-Times writer Thomas Conner gave it two out of four stars and stated "Legend might be the weak link; he's not the grittiest singer to be tackling this particular set list – he's often a boy in a man's studio here, especially when he gamely but lamely yeah's through the 12-minute arc of Bill Withers' wartime lament 'I Can't Write Left-Handed' – but his ease mostly makes a dynamic foil for the Roots' muscle and the frequent guest vocals". Zach Cole of URB's criticized Legend's singing as overdone and wrote that the album "run[s] the risk of coming across as entirely cheesy and contrived".Slant Magazine's Jesse Cataldo found it musically "hollow and brittle" and commented that "many of these treatments are good, but barely justify what amounts to a good-time vanity project for both acts".
Richard Trapunski of NOW viewed that Legend's "straightforward neo-soul delivery often plays it safe", but concluded "the expertly curated track list and funky arrangements make it more than a tossed-off vanity project". Despite finding its arrangements unadventerous, Los Angeles Times writer Todd Martens called Wake Up! "a respectable love letter, if not quite an urgent one, to artists who shouldn’t be overlooked" and commended Legend for "stretching out of his [comfort zone]... he packs far more spark here than he did on 2008’s 'Evolver'". David Amidon of PopMatters viewed that Legend "not only delivers his most focused effort yet, but his most diverse". Rupert Howe of Q cited Wake Up! as "one of the finest soul albums of recent times" and complimented Legend's vocal "versatility". Dave Simpson of The Guardian noted Legend's "emotional rawness" and wrote that "many of the tracks have a raw, driving feel along the lines of [Marvin] Gaye's Inner City Blues".The A.V. Club's Nathan Rabin commented that "The Roots’ tight playing serves the songs and their messages rather than the other way around, while Legend has mastered the art of singing expressively without over-emoting". Brad Wheeler of The Globe and Mail gave the album three out of four stars and commented that they "succeed" in their "attempt to keep these songs 'real' compared to the original versions".