Critics gave mixed reviews to the album. Some reviewers called B in the Mix: The Remixes a good remix compilation, while others argued that the album was conceived as a product and also criticized what they perceived as weak vocals. B in the Mix: The Remixes charted in countries such as Belgium, Japan, Italy and the United States, where it peaked at number four on the Billboard's Dance/Electronic Albums. As of November 2007, the album had sold one million copies worldwide, making it one of the best selling remix albums of all time. It received minimal promotion by Spears' standards. "And Then We Kiss" was released as the only single from the album in Australia and New Zealand.
On September 28, 2005, Jive Records announced through a press release that Spears would release a remix album titled Remixed. However, on November 8, 2005, it was reported by Jennifer Vineyard of MTV that the album was actually titled B in the Mix: The Remixes, and was going to be released on November 22, 2005. The album includes songs from her previous albums remixed by DJs such as Peter Rauhofer and Stuart Price. Price had previously remixed "Breathe on Me" from In the Zone for a limited edition bonus disc of Spears' 2004 compilation, Greatest Hits: My Prerogative. B in the Mix: The Remixes also includes one new song, "And Then We Kiss"; the song had previously been set to be included on a bonus disc of her 2005 DVD Britney & Kevin: Chaotic, but was left out for unknown reasons.B in the Mix: The Remixes had two covers. In the American edition, Spears does not appear on the cover; there is a butterfly instead. Vineyard noted this saying, "[the album] is being marketed in a more underground way than usually associated with a superstar act". In the international edition, Spears appears behind the butterfly.
The Bill Hamel remix of "Touch of My Hand" is a trance track with elements of ambient. Spears' voice has been described as "chopped up into skittering syllables and [...] becomes part of the beat". The album's fourth track, the Jacques Lu Cont's Thin White Duke Mix of "Breathe on Me" slows the beat from the original track making the song "darker and dirtier". The remix style was compared to songs by Kylie Minogue and Madonna. Dave Audé Slave Driver Mix of "I'm a Slave 4 U" consists of a guitar track and "quirky analog touches", according to Kurt Kirton of About.com. "And Then We Kiss" contains influences of euro-trance, techno and usage of synthesizers. The song blends dance-rock guitars and symphonic strings and closes with an orchestral overtone. Its lyrics talk about a kiss and the different sensations that the protagonist experiences, including trembling, crying and moaning. At the beginning she sings the lines "Lying alone / touching my skin" which suggest that the whole song may actually be a fantasy. The album's seventh track, the Valentin remix of "Everytime" contains a serious groove and pounding percussion, with usage of synthesizers. The Jason Nevins remix of "Early Mornin'" is considered the only hip hop song of B in the Mix: The Remixes.
Kurt Kirton of About.com highlighted the remixes of "Everytime" and "Don't Let Me Be the Last to Know", adding that the album would be better if it included more tracks. He summarized his review saying, "this is a decent release that should please any Britney fan and most club music fanatics". Barry Walters of Rolling Stone said the album was "even more redundant" than Greatest Hits: My Prerogative, but added that with the exception of "Toxic", "just about every original track is bettered here". Spence D. of IGN said, "If you had the choice to purchase only one Britney Spears' album, then this would be the one to spend your money on." Stephen Thomas Erlewine of Allmusic commented that "B in the Mix doesn't exactly erase the impression that Spears isn't in tune with her recording career". He also stated that on tracks such as "Toxic", "her flaws stand out just a bit too much [...] the instrumental hooks have been removed from the record, leaving Spears to carry the day—which she can't really do. [...] Overall this album sounds and feels like what it really is: a piece of product".MTV writer Bradley Stern praised the album, saying it "featured loads of excellent remixes stretching from '...Baby One More Time' to 'Toxic', but nothing shined quite as bright as the album's undeniable highlight: 'And Then We Kiss (Junkie XL Remix)'."
Gregg Shapiro of the Bay Area Reporter gave the album a mostly negative review, calling it "hazardous waste". He also noted that Spears's voice was "reedy, cold and mechanical" when stripped from the original mixes. However, he highlighted two tracks, saying, "Spears come closest to achieving dance-diva status on the Valentin remix of 'Everytime', while the Davidson Ospina 2005 remix of 'Baby One More Time' elevates the original bubblegum track to club classic". Mike Daniel of The Dallas Morning News called the Justice remix of "Me Against the Music" the best track of the album, but said it "has the feel of a hastily executed stopgap measure with almost no marketing-related thought behind it except to fulfill the once-every-two-years release cycle that's been established for Britney material."Entertainment Weekly writer Leah Greenblatt noted the remixes "amps already-aggressive singles like 'Toxic' and 'Me Against the Music' to brain-popping levels of synth spiraling", and transforms "sad-eyed slow jams like 'Everytime' and 'Don't Let Me Be the Last to Know' into Hi-NRG bursts. This party is BYORB (Bring Your Own Red Bull); without it, you might not be able to keep up."
In the United States, B in the Mix: The Remixes debuted at number one hundred thirty-four on the Billboard 200, selling 14,000 copies in its first week.It spent 11 weeks on the chart overall. The album also peaked at number four on Billboard's Dance/Electronic Albums, making it the first top four title on the chart since July 2002 that had more than 10,000 units sold. The album spent a total of twenty-one weeks on the chart. According to Nielsen SoundScan, B in the Mix: The Remixes has sold over 131,000 copies in the United States. The album also debuted on Belgium charts at number ninety-nine on the dated week of December 17, 2005, and also debuted at number fifty-nine on the Italian chart on the dated week of November 25, 2005. The album peaked at twenty-five in Japan, where it stayed eight weeks in that chart. As of November 2007, B in the Mix: The Remixes had sold one million copies worldwide, making it one of the best-selling remix albums of all time.
B in the Mix: The Remixes received little promotion compared to Spears' standards. A promotional 12-inch single titled Key Cuts from Remixed with five of the album's remixes was leaked more than two weeks before the album was released. A contest was launched on Spears' paid fan site for those who pre-ordered the album. The winner received a copy of Britney & Kevin: Chaotic, a bottle of Fantasy with an additional lotion and make-up kit and a personalized autographed picture of Spears. On November 22, 2005, a release party was held at an unspecified club in Los Angeles, California, organized by Spears' management and the webmaster of the fansite WorldOfBritney.com. It was a limited event to 500 people, including members of the fansite or her official fan club. Spears commented, "I just wanted to say that I love the idea of all my fans getting together to celebrate the release of my new album. I was happy to help! I hope you have a great night out at the club and dance all night long!".
Before being included on B in the Mix: The Remixes, "And Then We Kiss" was initially produced by Mark Taylor for Spears' fourth studio album, In the Zone (2003). It failed to be included on the album; however, after being remixed by Junkie XL for the remix album, it was released as the only single from the album in Australia and New Zealand. A promotional 12-inch single featuring a new version of the remix was also released. The remix received mostly positive reviews from music critics, with some noticing its potential to be a radio or club hit. "And Then We Kiss" failed to appear on any major charts. However, it peaked at number fifteen on the US Billboard Hot Dance Airplay. The version of the song produced by Taylor remained unreleased for years, until a new mix of the song labeled as the original version leaked online on September 2, 2011. After suggestions that it may be a fake, Taylor confirmed its authenticity to Bradley Stern of Muumuse.com on September 5, 2011.