"Don't Forget About Us" is a song co-written by Mariah Carey, Jermaine Dupri, Johntá Austin and Bryan-Michael Cox, and recorded by Carey for the re-release of her tenth studio album The Emancipation of Mimi(2005). It was co-produced by Carey, Dupri and Austin and released as the album's fifth single (fourth in North America) in late 2005. The song reached number one in Finland and the U.S., and the top forty elsewhere. It was nominated for two awards at the 49th Grammy Awards. Carey's vocals span from B2 to G6 in the song.

The song is a midtempo jam that harkens back to 1990s-styled R&B, and its protagonist regrets a failed relationship that never had a proper conclusion. Unlike "We Belong Together", another song from The Emancipation of Mimi, she is not very despondent, and has accepted that her ex-lover is now seeing someone else. However, she does not want him to forget what they had when they were together: "Nothing can compare to your first true love, so I hope this will remind you, when it's for real it's forever, so don't forget about us". She also reminds her ex-lover that no matter who his new girl is, "I bet she can't do like me, she'll never be MC." Carey has been accused of repeating formulas for her singles if they are successful. For instance, in the past, she was called out for making songs such as "Heartbreaker" (1999) and "Loverboy" (2001) too similar to other up-tempos like "Dreamlover" (1993) and "Fantasy" (1995). Several music critics have drawn parallels between "Don't Forget About Us" and "We Belong Together", the second and most successful single from The Emancipation of Mimi. Chuck Taylor of Billboardmagazine called the song "little more than a continuation of the previous hit ... On its own, "Forget" is a soulful, satisfying track, but it suggests that Carey has hit a creative wall." Bill Lamb of About.com, in a more positive summary of the song, wrote "It doesn't mess with the brilliant formula of "We Belong Together" ... [but] those wanting variety from Mariah Carey need to look elsewhere."

"Don't Forget About Us" was nominated at the 2006 BET Awards in the BET.com "Viewers' Choice" category. It was nominated for the 49th Grammy Awards for Best Female R&B Vocal Performance and Best R&B Song.

"Don't Forget About Us" officially impacted U.S. radio on October 11, 2005, but had already been added to many radio station playlists before that. It premiered on the radio and the internet in late September. It reached number 1 on the Billboard Hot 100 in its eleventh week and spent two weeks at the top, from December 25 to January 8. It replaced "Run It!" by Chris Brown, and was replaced by D4L's "Laffy Taffy". "Don't Forget About Us" stayed in the top forty for eighteen weeks and it also reached number 1 on several other Billboardcharts, including the Hot R&B/Hip-Hop Songs. It then tied Carey with Elvis Presley for the most number 1 singles in the U.S. by a solo artist with seventeen, she has since surpassed this record and is now behind only The Beatles, who hold the record with twenty.

The song's successful start to its U.S. chart performance was because of its strong radio airplay, but it advanced more slowly on the Hot 100 than Carey's previous two singles because of the lack of digital downloads. The album cut and several remixes were released to digital retailers on December 13, 2005 when the song was already number 2 on the Hot 100. The RIAA later certified "Don't Forget About Us" platinum. In Billboard's 2006 recap the single ended at number 50 on the top 100 singles list.

Outside the U.S, it topped the chart in Finland and reached the top twenty in the United Kingdom and Australia. It performed moderately in Europe.

The single's music video reunited Carey with Paul Hunter, director of the video for "Honey" (1997), and it jumps between two different time frames. The first of these involves a tearful Carey in the present, while the second invokes memories of a relationship with a former lover (played by Dolce & Gabbana model Christian Monzon). The video pays homage to actress Marilyn Monroe, whom Carey dressed up as in the music video for "I Still Believe" (1998): the shot in which Carey is in the pool with her leg protruding out of the water emulates an identical shot from Monroe's unfinished film Something's Got to Give(1962) in which she struck a similar pose.

The video was officially released promotionally on November 1, 2005, but was premiered by surprise on October 29 on MTV's Spanking Newseries. It reached number 1 on Total Request Live, where it eventually retired, on BET's 106 & Parkcountdown (for twenty-one non-consecutive countdowns), and on VH1's Top 20 Video Countdown.

The main remix of "Don't Forget About Us" was produced by Jermaine Dupri and is known as the Mr. Dupri mix. It features guest appearances from rappers Juelz Santana, Krayzie Bone and Layzie Bone, and Carey's parts are greatly reduced. It premiered on Chicago's B-96 FM on November 29, 2005. The Mr. Dupri mix later was added to iTunes Music Store for download, while several dance remixes (by Ralphi Rosario & Craig J., Quentin Harris and Tony Moran & Warren Rigg) were produced and made available for sale at other download retailers. The Mr. Dupri mix sold well enough to help "Don't Forget About Us" top Billboard's Hot Digital Songs chart, whereas the album cut reached only number 2 on the Hot Digital Tracks chart.

In January 2007, a new remix titled the Desert Storm remix, produced by DJ Clue (who also remixed "We Belong Together" and "Shake It Off") and featuring Fabolous and Styles P, was released to radio. It was originally supposed to be recorded with Cam'ron and Da Brat, but their recording session was cancelled after Cam'ron was injured during a shooting. On this version of the song, Carey's verses remain the same but although the chorus is altered, it keeps its original message and can be heard in its original lyrics once near the end of the song. The Desert Storm remix appeared on DJ Clue's album The Professional, Pt. 3. A video was also helmed for the Desert Storm mix. It can be found on Clue's official MySpace page and has shots of Carey, DJ Clue and Fabulous in the studio and out having fun.

European CD single

European CD single

Australian CD single

European CD maxi-single

UK CD maxi-single