Music critics gave a mixed reception to the song, with some praising its catchiness and fun production, while others criticized the EDM influence. "Slow Down" has achieved moderate success, reaching number 2 in Belgium (Flanders), while peaking inside the top 20 in Belgium (Wallonia), Russia, and South Korea. In the United States, the song peaked at number 27 on the BillboardHot 100, reached number-one on Billboard 's Hot Dance Club Songs chart, and it has been certified Platinum by the Recording Industry Association of America (RIAA) for selling over 1,000,000 units of the single in the country. On the Pop Songs component chart, it entered the top 10 and reached the position of number 7.
An 18-second sample of the song's pre-chorus features Gomez singing over a "pseudo-dubstep" instrumentation with influences of EDM. Lyrically, the song speaks of taking a relationship slowly rather than rushing into things.
On June 3, 2013, during a live chat on her YouTube channel, Gomez revealed that her debut solo studio album would be titled Stars Dance, and also revealed the album's track listing and cover art. During the same chat, the singer announced she would release "Slow Down" as the second single from the album, after "Come & Get It", and that fans would be able to download the song right after pre-ordering the album on iTunes. On August 13, the song was sent to mainstream radio in the United States, while a digital remixes EP was released the following week on Amazon.com. On September 6, a digital EP with "Lover in Me", "I Like It That Way" and a remix of "Come & Get It" as b-sides, was released through iTunes in some countries including Brazil, Norway, and Vietnam. The EP will be released in the United Kingdom on December 8.
Andrew Hampp of Billboard called the song "harmless, frothy fun", while complimenting its "pseudo-dubsteppre-chorusbreakdown, stretched-out staccato vocal loops and not-too-naughty-for Disney lyrics ("You know I'm good with mouth-to-mouth resuscitation")". Caryn Ganz of Rolling Stone noted that Gomez's producers "finally [gave] her tighter tunes" like "Slow Down", adding that it is "ripe for remixing." Writing for the Los Angeles Times, August Brown thought the production "Slow Down" is "rooted in today's pop-EDM default mode, but as that stuff goes, [the song] is pretty capable." PopDust contributor Christina Drill was critical towards the song, considering it "adequate-but-forgettable", and further stating: "the only thing that separates it from the faceless EDM masses? Selena cooing, 'You know I'm good with mouth to mouth resuscitation' in a way that's almost believable. A total whatever." Matthew Horton of Virgin Media deemed it "charmless". Some of the lyrics are a bit suggestive but there is nothing in them that would turn off any of her loyal fans."
After being released for instant digital download with the pre-order of Stars Dance, "Slow Down" charted in several countries, including Australia, where it peaked at number 91, and in Austria, staying on the country's chart for two weeks before peaking at number 71. The song has charted for 16 weeks in France, and has so far peaked at number 31. In the Ultratip charts from Belgium, it peaked at number 2 in Flanders and number 13 in Wallonia. On the Billboard Hot 100 in the United States, "Slow Down" peaked at number 27, and has been certified Platinum by the Recording Industry Association of America (RIAA). On the Pop Songs component chart, the song entered the top 10 and reached the position of number 7. As of July 2015, "Slow Down" has sold 1 million copies in the United States.
The accompanying music video for "Slow Down" was directed by Philip Andelman and filmed in Paris, France in May 2013. It leaked online on July 19, and was later uploaded to her official Vevo account. The video features Gomez sitting in the back seat of a 1964 Pullman 600 Mercedes-Benz. The car scenes are combined with her walking the streets of Paris dancing in a club dressed in a two piece outfit with backup dancers in front of pulsating neon lights. Sam Lansky of Idolator commented that the video has "no narrative, but it's Selena being grown-and-sexy, which is more than adequate narrative for me. It's a cherry on top of how fine the Stars Dance era has already been, and it augurs well for what's to come." A blogger for MuchMusic noted similarities on "Slow Down" to early music videos by recording artists Britney Spears, Janet Jackson and Jennifer Lopez.
When the music video for the song was leaked online, Keith Girard of celebrity gossip site The Improper wrote that the music video for "Slow Down" had elements of the death of Diana, Princess of Wales. Keith says that "Selena Gomez’s new video for song “Slow Down” contains some eerie parallels to the death of Princess Diana. Selena races through the Paris streets in a vintage Mercedes similar to Diana’s on the night she was killed in a car crash." Caroline Bologna of Hollywood.com picked up on the matter on the same day and mentioned how the footage of the vintage car speeding through tunnels is similar to the princess' death.