Released the same year, their debut album Don't Forget went to number two on the Billboard 200, only to be outdone by the follow-up, 2009's Here We Go Again. While continuing to turn out hit albums, they served as a judge on the U.S. version of TV talent competition The X Factor (2012 to 2013), had a Top 40 hit with their pop version of "Let It Go" from the soundtrack to Disney's Frozen (2013), and became a Grammy nominee (Best Pop Vocal Album) thanks to their fifth full-length, 2015's Confident. Lovato reached number six on the Hot 100 in 2017 with "Sorry Not Sorry" from Tell Me You Love Me, their sixth consecutive Top Five album. A second career Grammy nomination followed in 2019 for the previous year's "Fall in Line," a duet with Christina Aguilera. Having publicly struggled with substance abuse and mental-health issues along the way, Lovato is a longtime spokesperson for causes including anti-bullying and mental-health awareness.

Born in 1992 in Albuquerque, New Mexico, Lovato was raised in a household that included their mother (a former Dallas Cowboys Cheerleader) and two sisters, the youngest of whom launched her own acting career in 2008. Lovato started out as an actor, starring as a cast regular on Barney and Friends before finding their way onto the Disney Channel with a recurring role in As the Bell Rings. Their debut album, Don't Forget, featuring songs co-written by the Jonas Brothers, was released by Hollywood Records several months after the premiere of Camp Rock, a 2008 Disney Channel movie starring Lovato and the Jonas siblings. Don't Forget debuted at number two, confirming Lovato's status as a star in their own right, and was followed in 2009 by the chart-topping Here We Go Again. Meanwhile, they continued to act, appearing in a popular 2010 sequel to Camp Rock and starring in their own Disney series, Sonny with a Chance, which aired for two seasons.

In 2011, Lovato released the studio album Unbroken, featuring the Toby Gad-produced single "Skyscraper." It became the biggest hit since their Camp Rock days, nesting at number ten on the Billboard Hot 100 and going platinum. The second single, "Give Your Heart a Break," peaked slightly lower at number 16 but was a bigger seller, eventually certifying as three-times platinum in the U.S. alone. Unbroken also featured co-starring roles for Timbaland and Missy Elliott on "All Night Long" and Jason Derulo on "Together."

Lovato's comeback continued in 2012 when they, along with Britney Spears, signed on to be one of the four judges on the second season of the U.S. version of The X Factor. It debuted in the fall of 2012, and Lovato's role was a success, leading to their return for the 2013 season. Prior to the season's launch, they released their fourth album, Demi, which appeared in May 2013 -- preceded by the single "Heart Attack," which peaked in the Top Ten. A pair of subsequent singles reached the Top 40: "Neon Lights" and "Really Don't Care" (the latter featuring Cher Lloyd). Lovato hit the Top 40 yet again with a contribution to another Disney vehicle, this time a cover version of Idina Menzel's "Let It Go" that was released as the lead single for the massive hit Frozen. Lovato also entered the best-selling books chart with Staying Strong: 365 Days a Year, a collection of their thoughts and quotes from those who inspired them during their struggles with addiction and depression. During 2014, they had a recurring role on the TV show Glee and headlined two world tours.

The following July, Lovato released "Cool for the Summer," the Max Martin and Wolf Cousins-produced lead single for their fifth studio album, Confident. The brassy title track was also issued as a single a few weeks before the record's October 2015 release. Other collaborators on the album included Iggy Azalea and songwriter Savan Kotecha, who also contributed to "Cool for the Summer." In addition to a Grammy nomination, Confident peaked at number two on the Billboard 200. In 2017, Lovato contributed vocals to Cheat Codes' "No Promises" and Jax Jones' "Instruction" before releasing their own single, "Sorry Not Sorry." It was the first glimpse of their sixth full-length album, Tell Me You Love Me, which appeared in September 2017 and reached number three on the Billboard 200. That November, they also paired with Luis Fonsi for the non-album single "Échame la Culpa." In 2018, Lovato joined Christina Aguilera on the track "Fall in Line" and delivered their own addiction-themed single, "Sober." More singles, including "I'm Ready" featuring Sam Smith, landed them in the Top 40 in 2020. Just prior to the 2020 presidential election, they released the protest song "Commander in Chief."

Lovato launched a documentary series called Demi Lovato: Dancing with the Devil in 2021. Accompanying the film was Dancing with the Devil...The Art of Starting Over, their seventh studio album, which was billed as "the non-official soundtrack to the documentary" and was preceded by the single "What Other People Say," a duet with Sam Fischer. A month after the release of Starting Over, Lovato came out as non-binary.