After the cancellation of Carey's thirteenth studio album/second remix album Angels Advocate, speculation began to shift onto an alleged Christmas album. Carey began recording the album on April 9, 2010 at Jermaine Dupri's Southside Studios in Atlanta. Dupri told Rap-Up: "The song of the decade crew is back in the lab, this [is] the first day of the new shit". Carey also confirmed the news, stating: "To all the Lambs in the land...Finally!!! Me & Jermash are in his studio re-living the splendor, working on new ish". Fashion photographer David LaChapelle told The Times on April 24, 2010 that he shot the Christmas album's artwork, thus confirming that Carey was indeed planning to release her second holiday album. It was revealed that long-time collaborators for the project include Jermaine Dupri, Bryan-Michael Cox, Johntá Austin and Randy Jackson. Roger Friedman of Showbiz 411 said about the album, "Anyway, Mariah's Christmas album is said to be very lush, with lots of strings and no hip hop. A lot of it is said to be 'live' and there's an orchestra. So let's chew on that news, and calm down about the other. And believe me, she won't be announcing anything at Radar Online owned by the National Enquirer. That won't be happening!"
It was later announced that Carey had worked with Broadway collaborator Marc Shaiman, with Carey saying that he was her favorite collaborator since her days with Walter Afanasieff. During a press conference in Seoul, South Korea, in August 2010, Island Def Jam executive Matt Voss announced that the Christmas album would be out on November 2. Several days later, the album's title was revealed. The II represents the follow-up to 1994's multi-platinum Merry Christmas album. An accompanying DVD would also be released. In September 2010, Bryan-Michael Cox confirmed through UStream that there is a song on the album called "Oh Santa!" and that Carey still has one song left to record. It was later announced that "Oh Santa!" will serve as the album's lead single. The song premiered on AOL Music on October 1, 2010.
In November 2011 in an interview with Extra, Carey stated that she wanted to re-release the album containing festive collaborations with Justin Bieber and John Legend.
On October 20, 2010 Mariah appeared on HSN for an interview about the album and she previewed six tracks from the album. On November 1, 2010, Mariah made a pre-recorded guest appearance on The Ellen DeGeneres Show to talk about her pregnancy and album which aired on November 2, 2010. On November 2, 2010, Carey also appeared on Lopez Tonight. On 19 November Mariah recorded a performance of "Oh Santa!" for NBC Rockefeller Center Christmas Tree Lighting which was shown on November 30. Carey made various television appearances throughout December to promote the album. She starred in ABC's Mariah Carey: Merry Christmas to You special, which aired on December 13 at 9/8c. The special drew 4.89 million viewers. Mariah also performed at the "Christmas In Washington" special on TNT to air on 12/17. On December 25, she was featured performing the song throughout the day on ESPN and ABC, first on ABC's Walt Disney World Christmas Day Parade special, then in a music video promoting the day's NBA games on both networks.
Mariah also put out a videos for "Auld Lang Syne", a studio video of her and her mother Patricia Carey singing "O Come All Ye Faithful/Hallelujah Chorus". A music video for a duet version of "When Christmas Comes" (with John Legend) was released in 2011, and in 2012 a lyric video for "Christmas Time Is In Air Again" was uploaded to VEVO.
"Oh Santa!" is the lead single from the Christmas album. The song is written by Jermaine Dupri, Bryan-Michael Cox and Carey herself. The song premiered on AOL Music on December 13, 2010. It has been sent to radios and made available for digital downloads since December 21, 2010. For the week ending December 11, 2010, "Oh Santa!" debuted at number twelve on Billboard's Hot Adult Contemporary Tracks chart, becoming Carey's highest debut on that chart in her 20-year career. The song jumped to number one on the Adult Contemporary chart the following week, making it the fastest rise to number one in that chart's history. It remained at #1 for 4 weeks.
"When Christmas Comes" was re-worked into a duet with John Legend. It was released as a digital download on January 3, 2011. It was sent to Urban radio on the same day. The music video for "When Christmas Comes" was filmed in November 2011. The music video premiered on A Very BET Christmas on December 11, 2011 on the BET channel.
During an interview with USA Today, Carey confirmed that she had recorded the video to "O Come All Ye Faithful." The video premiered January 16, 2011.
On December 24, 2011, Carey posted a video for "Charlie Brown Christmas" on her YouTube channel. The clip features scenes from the A Charlie Brown Christmas holiday program.
"Christmas Time Is in the Air Again" was used in VH1 Save the Music's holiday campaign starting from November 27, 2012. Carey performed the song on NBC's Christmas in Rockefeller Center, on Wednesday, November 28, 2012.
At Metacritic, which assigns a normalized rating out of 100 to reviews from mainstream critics, the album received an average score of 60, based on 8 reviews, which indicates "mixed or average".
Both Allmusic and Rolling Stone gave the album three stars, with Caryn Ganz of Rolling Stone writing "Sixteen years have passed since Mariah Carey released her first blockbuster holiday album, but she hasn't lost her desire to dress up in a Santa suit or the silky flexibility of her voice...Half of the disc's new originals are ballads [and] thick with gooey orchestration... but Mariah bops to a schoolyard-chant beat on "Oh Santa!" and digs out a retro groove for "When Christmas Comes." Ganz concluded that although some songs on the album are lacking, "the LP's warm heart is in the right place." Eric Henderson of Slant Magazine gave the album a mixed review, calling the album "adventureless", he wrote, "Aside from a few tracks co-produced by Jermaine Dupri, Carey's notions of what a holiday album is are exactly as they were 16 years ago. Ditch the hip-hop beats, heap on the figgy orchestral pudding. Pass those synthesizers to the left, gather around the brass section and the little drummer boy." Sean Fennessey of The Washington Post also gave a mixed critical reception to the album. Comparing the album to Carey's 1994's Merry Christmas, Fennessey suggested that, while Merry Christmas II You sees the "return [of] her piercing, five-octave vocal range to its glossy, meretricious roots", none of the new songs are as exciting or timeless as "All I Want for Christmas Is You". The album got 4 out of 5 stars from About.com, with reviewer Bill Lamb describing the album as "relaxed [and] comfortable", and, consequently, "very engaging." Lamb continues, "Some of the best moments evoke a party atmosphere. 'Oh Santa!' is perfect music for a party with friends. Don't be surprised if you find yourself singing along. Mariah Carey's version of music from 'A Charlie Brown Christmas' has an air of relaxed intimacy with breathy, jazzy vocals that will warm your holiday heart. The live version of 'O Holy Night' from WPC in south central Los Angeles will cause chills in its live simplicity. It is an opportunity to hear Mariah Carey tackle some deeper, throatier tones."
The Houston Chronicle gave Merry Christmas II You three stars out of four, lauding the singer's vocal form on the album. Joey Guerra writes, "Carey sounds better than she has in a longtime throughout Merry Christmas II You, which keeps her in a swirl of gospel choruses and lush production. Her belting is strong, and she doesn't overdo the breathy coos." Guerra also had strong praises for a number of songs, calling "Oh Santa!" "irresistible", and writing, "'Christmas Time Is in the Air Again' boasts swooping notes and tasteful strings, and 'When Christmas Comes' plays like a holiday spin on the brassy R&B tunes that highlighted Carey's The Emancipation of Mimi disc... The solemn 'One Child' sounds a bit like a Michael Jackson tune (complete with kid chorus). It's a bit overwrought, but it's hard not to be swayed by the sweetness." The reviewer concluded that "Merry Christmas II You should boost the singer's career."
In its opening week in the United States, the album debuted at #4 on the Billboard 200 with sales of 56,000 copies, surpassing the opening week sales of Carey's previous holiday album Merry Christmas of 45,000 copies 16 years prior, and making Merry Christmas II You Carey's 16th top 10 album. The album also debuted at #1 on the R&B/Hip-Hop Albums chart, making it only the second Christmas album to top this chart, and also hit number #1 on the Holiday Albums Chart. On January 11, 2011, Merry Christmas II You was certified Gold by the Recording Industry Association of America (RIAA), denoting shipments of 500,000 units. As of April 2013, the album has sold 523,000 copies in the United States.