The album was released in the United States on August 17, 1999, and in the United Kingdom on October 1, 1999.
"All That I Can Say", "Deep Inside", "Your Child", and "Give Me You" were the albums commercial singles in the United States. "As"—Blige's collaboration with George Michael—was released as the lead single everywhere else worldwide. Three singles from the album charted on the Billboard Hot 100: "All That I Can Say" at number 44, "Deep Inside" at number 51, and "Give Me You" at number 68. All four United States singles charted on the Billboard Hot R&B/Hip-Hop Singles & Tracks: "All That I Can Say" at number six, "Deep Inside" at number nine, "Your Child" at number 23, and "Give Me You" at number 21.
The album debuted at number two on the US Billboard 200 chart, with first-week sales of 239,000 copies in the United States. It also entered at number one on Billboard's Top R&B/Hip-Hop Albums chart, becoming Blige's fourth album to top the chart.Mary spent 57 weeks on the Billboard 200 and 69 weeks on the Billboard Top R&B/Hip-Hop Albums. In the United Kingdom, the album debuted at number five on the UK Albums Chart.
Q gave the album four out of five stars and stated "Blige can turn from sassy to agonized to vulnerable in the space of a single phrase [...] The Queen Of Hip Hop Soul remains classy and invincible".Craig Seymour of Spin praised its classicist influences and called Mary "emotionally gripping and stylistically diverse", writing that "[Blige's] assured blues moans, gospel shouts, and jazzy inflections graph the history of African-American music".Chicago Tribune writer Greg Kot noted "a more organic feel" in its production, which he viewed as less "uninspired" than on Blige's previous albums.Entertainment Weekly's Anthony DeCurtis complimented Blige's vocal embellishments and the album's "lush and spare" arrangements, stating "Musically, Mary is essentially a long, soulful, ballad-tempo vamp over which Blige alternately — and sometimes simultaneously — tells tales of faithless love, preaches the gospel of female strength, and determinedly clings to hope".The Source complimented Blige's "pure emotion" and stated "she dares to break the hip-hop soul template she helped create, and do something different. Something our loop-weary souls need". Steve Jones USA Today commended Blige for "making you feel rather than merely hear what she's singing about", adding that she "continues to separate herself from her peers, conveying a wide range of emotions without becoming whiny, petty or overwrought".
Despite viewing its strength as "more in how Blige sings the songs than the songs themselves", Los Angeles Times writer Soren Baker commented that "the lively, supple instrumentation only adds to the force of her already dominating delivery" and noted "a more soul-stirring, straightforward R&B attitude than the hip-hop/R&B hybrid of her earlier collections".Rolling Stone writer Touré gave the album four out of five stars and commented that "Blige seems to have moved away from the Terry McMillan once-again-he's-breaking-my-heart mantra to, perhaps, an Oprah love-your-spirit ethos".Christopher John Farley of Time wrote that "Mary is somewhat inconsistent in song quality, but Blige's soul-singed vocals save the weaker material".Ann Powers of The New York Times viewed that the album exemplifies a "new conscience" of feminine themes in contemporary R&B at the time, adding that "if Mary gestures toward an older, non-hip-hop audience, it also makes the claim for Ms. Blige's canonization within the rhythm-and-blues hall of fame". In his consumer guide for The Village Voice, critic Robert Christgau gave the album an A- rating, indicating "the kind of garden-variety good record that is the great luxury of musical micromarketing and overproduction". He commented that "Rather than hating playas, she's bored with them [...] all that she can say is that she's ready to love someone serious and walk away from anyone who isn't".
In a retrospective review for The Rolling Stone Album Guide, music writer Tom Moon of Rolling Stone gave the album three-and-a-half out of five stars and viewed it as an improvements over Blige's previous album, commenting that it "more fully realizes Blige's vision for Share My World".Allmusic editor Stephen Thomas Erlewine gave it four out of five stars and complimented its "sheer classiness", writing that "There's still grit in the music, but it's been glossed over with a polished production". Erlewine described it as "a rewarding, engaging way to mature" and wrote that "Blige's voice is richer and her skills have deepened, and her new songs, while not as streetwise, are worthy of her talents".
Spin ranked the album number 15 in its year-end list of best albums. Blige won and was nominated for many awards for this album.
She was nominated for 2 MTV Europe Music Awards for Best Video and Best Song ("As" with George Michael).
In 2000 Blige was nominated for a Brit Award for Best International Female Solo Artist.
3 Grammy Awards nominations for Best R&B Vocal Performance - Female ("All That I Can Say"), Best R&B Vocal Performance by a Duo or Group ("Don't Waste Your Time" with Aretha Franklin), and Best R&B Album (Mary).
In 2001 Blige was nominated for a Soul Train Music Award for Best Female R&B/Soul Single for "Your Child".
Blige won a Soul Train Music Award for Best R&B/Soul Album, Female (Mary) and was also nominated for Best R&B/Soul or Rap Album.
Blige also won 2 Soul Train Lady of Soul Awards for Solo R&B/Soul Album of the Year for Mary and R&B/Soul or Rap Song of the Year for "All That I Can Say". She was also nominated for Best Solo R&B/Soul Single for "All That I Can Say".
Blige also won the first ever BET award for Best Female Artist in 2001 for Deep Inside.