The Billboard Hot 100 is a chart that ranks the best-performing singles of the United States. Published by Billboard magazine, the data are compiled by Nielsen SoundScan based collectively on each single's weekly physical and digital sales, and airplay. In 2005, there were eight singles that topped the chart in fifty-three issues of the magazine, the second lowest of any year.

During the year, five acts achieved their first US number-one single, either as a lead artist or featured guest: Mario, Olivia, Gwen Stefani, Carrie Underwood, and Chris Brown. Stefani earned her first number-one single in the United States this year, although she had been with band the No Doubt since 1986. Hip hop artist Kanye West gained his first number-one single, "Gold Digger", as lead artist; West previously had a number-one single with "Slow Jamz", a 2004 song by rapper Twista. Two acts, Underwood and Brown, scored a number-one debut single this year. Mariah Carey was the only act to have more than one number one song, with her earning two.

Mariah Carey's "We Belong Together" is the longest-running single of 2005, topping the Billboard Hot 100 for 14 non-consecutive weeks. The single is tied with "I Gotta Feeling" by American group The Black Eyed Peas for the longest-running number-one single of the decade. As of 2018, "We Belong Together" was tied for the second longest-running number-one single in the entire Hot 100 era behind Boyz II Men's and Carey's 1995 single "One Sweet Day", which spent sixteen weeks at number one. Despite being surpassed by three other songs during the years, "We Belong Together" still is one of the songs with the most weeks spent at number one in the entire Hot 100 history. West's "Gold Digger" is the second longest-running, having peaked the chart for 10 consecutive weeks. Other singles with extended chart runs include R&B singer Mario's "Let Me Love You", his best-performing song to date, and rapper 50 Cent's "Candy Shop", each spent nine straight weeks at number one.

Carey is the only artist to have earned two number-one singles in 2005 after "Don't Forget About Us" topped the chart in the final calendar issue of Billboard Hot 100. "Don't Forget About Us" is Carey's 17th number-one single, placing her third in the list of acts with most number ones in the United States at the time, behind only The Beatles and Elvis Presley. "We Belong Together" is the best-performing single of the chart year, topping the Top Hot 100 Hits of 2005; this gave Carey her first number-one single in the year-end chart.

Chart history

Key

†	Indicates best-performing single of 2005

No.	Issue date	Song	Artist(s)	Reference(s)
911	January 1	"Let Me Love You"	Mario
	January 8
	January 15
	January 22
	January 29
	February 5
	February 12
	February 19
	February 26
912	March 5	"Candy Shop"	50 Cent featuring Olivia
	March 12
	March 19
	March 26
	April 2
	April 9
	April 16
	April 23
	April 30
913	May 7	"Hollaback Girl"	Gwen Stefani
	May 14
	May 21
	May 28
914	June 4	"We Belong Together"†	Mariah Carey
	June 11
	June 18
	June 25
915	July 2	"Inside Your Heaven"	Carrie Underwood
re	July 9	"We Belong Together"†	Mariah Carey
	July 16
	July 23
	July 30
	August 6
	August 13
	August 20
	August 27
	September 3
	September 10
916	September 17	"Gold Digger"	Kanye West featuring Jamie Foxx
	September 24
	October 1
	October 8
	October 15
	October 22
	October 29
	November 5
	November 12
	November 19
917	November 26	"Run It!"	Chris Brown
	December 3
	December 10
	December 17
	December 24
918	December 31	"Don't Forget About Us"	Mariah Carey

Number-one artists

List of number-one artists by total weeks at number one

Position	Artist	Weeks at No. 1
1	Mariah Carey	15
2	Kanye West	10
	Jamie Foxx
4	Mario	9
	50 Cent
	Olivia
7	Chris Brown	5
8	Gwen Stefani	4
9	Carrie Underwood	1

See also

• 2005 in music
• List of Billboard number-one singles
• Billboard Year-End Hot 100 singles of 2005
• List of Billboard Hot 100 number-one singles of the 2000s