The song peaked at number 13 on the US Billboard Hot 100 and hit number one on both the US BillboardHot Rap Songs and Hot R&B/Hip-Hop Songs charts. The song has since been certified triple Platinum for three million digital sales, and has sold over two million copies in the US as of October 2012. A music video directed by Australian director Nabil Elderkin was released on June 6, 2012. The highly-stylized video shows a long take of all four rappers featured on the song, along with other GOOD Music recording artists such as Cyhi the Prynce, Kid Cudi, Mr. Hudson and Teyana Taylor in cameos. The video features the rappers giving their verses and dancing around, with deliberate editing to make it appear as if they are disappearing and reappearing behind walls. The video received positive reviews from critics.
The song was originally supposed to be released on Good Friday, but was released a day early on Thursday, following the release of the West and DJ Khaled collaboration track "Cold". The track was premiered by Funkmaster Flex's Hot 97 radio show and was released onto the Internet the following day onto West's official website. The song serves as the first official single from Cruel Summer, an album by West's record label GOOD Music. The release of the track continued West's GOOD Fridays, a music giveaway that provided free MP3 downloads every week, which had been on hiatus since December 2010. The song features Big Sean and Pusha T, rappers both signed to West's GOOD Music, along with 2 Chainz, all delivering a verse each along with West. Speaking about his feature, 2 Chainz stated that "I've done a lot of work with 'Ye for, like, a year now, and it was one of those songs where I called him and I told him, 'Man, play my verse over the phone because I don't remember.' That's a good look to add to the résumé, for real." According to 2 Chainz, he had no idea that the song was going to be a single.
The song was produced by Lifted, with additional production from West, Mike Dean, Mike Will Made It, and Anthony Kilhofer. Lifted had produced the beat in November 2011, and his manager was responsible for playing the beat to West which led to him wanting to work with Lifted. Furthermore, Kanye played the embryotic version to Anthony "The Twilite Tone" Khan and additional production was done including but not limited to samples and the part in which Kanye raps over.  Both Pusha T and Big Sean recorded their verses in January 2012 and the song was mixed and finalized in March. Producer Hit-Boy, known for producing West's "Niggas in Paris", commented that "It's fresh, it's new, it's something you haven't heard before. It's elements of trap, but it's just some fresh, new-sounding stuff. I'm excited about it. I wish I did it, but I didn't".
Sonically, "Mercy" blends Southern rap elements with dancehall vibes. "Mercy" starts with a vocal sampling from the late Fuzzy Jones. The island-laced intro gives way to an eerie-sounding bass track, sparse drums, piano keys and a Scarface film sample. The track features an undulating beat, "threaded through the entire song and it almost mimics an eerie piano. There's also an omnipotent voiceover that shows up every once and a while [sic], too." Playing off a hook (sampled from YB's song "Lambo") about a "two-seat Lamborghini". West's posse references Sarah Palin, Rick James and Ms. Pac-Man. At about three minutes in, the song switches up and turns into an electronic dance music track. The beat then slows down, and "despite the jarring difference in timing, it's like a song within a song."
Lyrically, Big Sean picks up where "his "Dance (A$$)" single left off with strip-club-inspired bars, Pusha laments about his "exotic car collection", while Kanye baits "lesser rappers, flashing his riches and model girlfriends." With no real "concept in place", 2 Chainz closes things out with a "free associative verse where spits about his black diamond chain and Louis Vuitton backpack and expensive strains of marijuana." Sean repeats the phrase "swerve" several times throughout the song.LA Weekly journalist Brian McManus noted that the track contains references to suicide doors, which West has previously discussed in his song "Can't Tell Me Nothing.
"Mercy" received mostly positive reviews from music critics. Idolator stated that the track "falls somewhere in the middle of the pack among West's previous G.O.O.D. Friday singles – it's nowhere near as much fun as "Good Friday" or as seductive as "Devil in a New Dress". Amy Sciarretto of Popcrush stated that the track was "great", and that "even with four rappers laying down verses on the song, it's a compact, tightly constructed tune that feels like a series of freestyle raps that flow into one another flawlessly." Corban Goble of Stereogum mused that the song "is a giant, lurching thing where the rappers trade bravado-filled verses around a syrup-music inspired hook." Jayson Rodriguez of XXL stated that "the public may have seen this idea and presentation before, but the music is still next level. It's fitting that Kanye could bring together this cast and execute the finished product this well. Still, Wednesday's spontaneous release of "Cold" was a bit much more exhilarating both musically and dramatically." Josiah Hughes of Exclaim! mused that "the track most likely sounds just as you'd expect, all expensive, epic-sounding production, some slowed-down samples and an aggressive synth beat. There's also an appearance of Kanye's obnoxious new trademark huuuuh?" Kia Makarechi of The Huffington Post wrote that "lyrically, 'Mercy' doesn't have much to it, but it's a competent piece of braggadocio."
In Complex's list of the best 25 lines of the first half of 2012, 2 Chainz' line "Horse power, horse power/All this Polo on I got horse power" was listed as the 14th best, and West's line "Don't do no press, but I get the most press, kid/Plus, yo, my bitch make your bitch look like Precious" was listed as the seventh. Complex went on to name "Mercy" the best song of 2012.Rolling Stone named the song the 6th best song of 2012.XXL named it one of the top five hip hop songs of 2012.
"Mercy" debuted on the Billboard Hot 100 at position 38, and achieved a peak position of 13. The song peaked at number one on both the Hot Rap Songs and Hot R&B/Hip-Hop Songs charts. The song also became a top 50 song in both Canada and in the UK (on its R&B chart).
West released a black-and-white image of a Lamborghini on his Twitter account, serving as promotion for the video. The music video was directed by prior West collaborator Nabil Elderkin, who has helmed prior West videos such as "Welcome to Heartbreak" and "Paranoid". It was filmed in a mall's parking garage in Doha, Qatar, while West was producing his short film Cruel Summer. On June 6, West "unleashed the deceptively minimalist video" onto his Website.
The video was shot in a wide frame with the artists in what looks like a "parking garage, rapping as the camera pans across the room" with a Lamborghini Gallardo LP560-4 featured in the background. The video contains numerous cameos by other artists signed to GOOD, including Kid Cudi, Cyhi the Prynce, Teyana Taylor, Hit-Boy, D'banj and Mr. Hudson. Taylor whips her black dress back and forth, Cyhi poses behind a pair of sunglasses, Mr. Hudson stares intently at the camera, and D'banj and Cudi dance along with their own unique moves. In the video Big Sean is wearing a turban-styled headpiece as he raps first. At the end of the clip a Lamborghini Gallardo moves past the screen and the artists are gone from the scene after it passes by. Marc Hogan of Spin praised the video, writing that "as with the track itself, the visuals at first might not appear to involve anything flashy – just West and friends, all lurking about and looking chic in stark black-and-white. But there's one big exception: If the highlight of the audio is the moment where the synths lift off right before West's laconic verse, then that's where the video peaks, too – watch closely, or you'll miss two Wests lip-syncing for the price of one!"Pitchfork Media's Carrie Batton commented that "it's a simple but cinematographically impressive black-and-white clip with lots of leather and keffiyehs and sharp angles."
The song was first performed by West at the London stop of his 2012 Watch the Throne Tour, with West performing his portion of the song. Big Sean performed the song with Pusha T and 2 Chainz during his 2012 setlist at Summer Jam, which was described as a "possibly a show-stealing performance". At the 2012 BET Awards, the song was performed by all four rappers. Big Sean, Pusha T, 2 Chainz filed out one by one to deliver their verses, performing in front of a stage-set model of a Lamborghini. Though Los Angeles Times's Randall Roberts noted that it wasn't "until West moved into his hit "Cold" that things got great", with the "music dropping, the rapper moved into a freestyle on "New God Flow" that culminated in a foot-stomping breakdown."