iHeartRadio Music Festival 2018: All the stars that were there!

Stars go to Vegas!

The 2018 iHeartRadio Music Festival kicked off at T-Mobile Arena on Friday night, and a slew of the biggest stars in music and TV were on-hand for the hottest party in Las Vegas this weekend.

Mariah Carey stole the show both onstage and on the red carpet, where she rocked a teeny studded black mini dress that showed off her slimmed-down figure. The "GTFO" singer was all smiles for her big night, where other stars like Sarah Hyland, Sara and Erin Foster and Paula Abdul were also in attendance.

Jack White, Fleetwood Mac and Childish Gambino were among the other musicians to take the stage.

Check out the gallery below for an updating roundup of the stars at the 2018 iHeartRadio Music Festival:

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iHeartRadio Music Festival 2018: All the stars in attendance
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iHeartRadio Music Festival 2018: All the stars in attendance
LAS VEGAS, NV - SEPTEMBER 22: Mariah Carey poses in the press room during the iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Tara Ziemba/FilmMagic)
LAS VEGAS, NV - SEPTEMBER 22: Mariah Carey poses in the press room during the iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Tara Ziemba/FilmMagic)
LAS VEGAS, NV - SEPTEMBER 22: Carrie Underwood attends the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by JB Lacroix/WireImage)
LAS VEGAS, NV - SEPTEMBER 22: Justin Timberlake attends the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by JB Lacroix/WireImage)
LAS VEGAS, NV - SEPTEMBER 21: Paula Abdul attends the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by Kevin Mazur/Getty Images for iHeartMedia)
LAS VEGAS, NV - SEPTEMBER 22: Shawn Mendes attends the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by JB Lacroix/WireImage)
LAS VEGAS, NV - SEPTEMBER 22: Kelly Clarkson attends the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by JB Lacroix/WireImage)
LAS VEGAS, NV - SEPTEMBER 21: John McVie, Mick Fleetwood, Mike Campbell, Stevie Nicks, Christine McVie and Neil Finn of Fleetwood Mac attend the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by JB Lacroix/WireImage)
LAS VEGAS, NV - SEPTEMBER 22: Shawn Mendes (L) and Justin Timberlake perform onstage during the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Kevin Winter/Getty Images for iHeartMedia)
LAS VEGAS, NV - SEPTEMBER 21: Jared Haibon (L) and Ashley Iaconettiattends the iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by Rich Fury/Getty Images for iHeartMedia)
LAS VEGAS, NV - SEPTEMBER 21: Jared Haibon (L) and Ashley Iaconetti pose in the press room during the iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by David Becker/Getty Images for iHeartMedia)
LAS VEGAS, NV - SEPTEMBER 21: Ryan Seacrest speaks onstage during the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by Kevin Winter/Getty Images for iHeartMedia)
Actor K.J. Apa arrives in the press room for day 2 of iHeartRadio Music Festival in Las Vegas, Nevada on September 22, 2018. (Photo by CHRIS DELMAS / AFP) (Photo credit should read CHRIS DELMAS/AFP/Getty Images)
LAS VEGAS, NV - SEPTEMBER 22: Brie Bella and Nikki Bella pose in the press room during the iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Tara Ziemba/FilmMagic)
LAS VEGAS, NV - SEPTEMBER 21: Sarah Hyland attends the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by JB Lacroix/WireImage)
LAS VEGAS, NV - SEPTEMBER 22: Dua Lipa poses backstage during the 2018 iHeartRadio Music Festival Daytime Stage at the Las Vegas Festival Grounds on September 22, 2018 in Las Vegas, Nevada. (Photo by Denise Truscello/Getty Images for iHeartMedia)
LAS VEGAS, NV - SEPTEMBER 21: Sarah Hyland and Wells Adams attend the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by JB Lacroix/WireImage)
LAS VEGAS, NV - SEPTEMBER 21: Jana Kramer poses in the press room during the iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by Tara Ziemba/FilmMagic)
LAS VEGAS, NV - SEPTEMBER 21: Jana Kramer attends the iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by Rich Fury/Getty Images for iHeartMedia)
Singer Miguel arrives in the press room for the iHeartRadio Music Festival on September 21, 2018. (Photo by CHRIS DELMAS / AFP) (Photo credit should read CHRIS DELMAS/AFP/Getty Images)
LAS VEGAS, NV - SEPTEMBER 22: Darren Criss attends the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by Tara Ziemba/FilmMagic)
LAS VEGAS, NV - SEPTEMBER 21: Sara Foster and Erin Foster attend the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by Kevin Mazur/Getty Images for iHeartMedia)
LAS VEGAS, NV - SEPTEMBER 21: Ireland Baldwin poses in the press room during the iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by Tara Ziemba/FilmMagic)
LAS VEGAS, NV - SEPTEMBER 21: Ryan Seacrest (L) and Paula Abdul pose during the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by Kevin Mazur/Getty Images for iHeartMedia)
LAS VEGAS, NV - SEPTEMBER 22: Sarah Hyland attends the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Kevin Mazur/Getty Images for iHeartMedia)
LAS VEGAS, NV - SEPTEMBER 21: Iggy Azalea attends the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by JB Lacroix/WireImage)
British actor Jeremy Gilley (L) and Mike Posner (R) arrive in the press room for the iHeartRadio Music Festival on September 21, 2018. (Photo by CHRIS DELMAS / AFP) (Photo credit should read CHRIS DELMAS/AFP/Getty Images)
LAS VEGAS, NV - SEPTEMBER 21: Ryan Seacrest (L) and Stevie Nicks attend the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by Rich Fury/Getty Images for iHeartMedia)
LAS VEGAS, NV - SEPTEMBER 21: Tanya Rad (L) and Becca Tilley pose in the press room during the iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by Tara Ziemba/FilmMagic)
LAS VEGAS, NV - SEPTEMBER 21: Dinah Jane attends the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by JB Lacroix/WireImage)
LAS VEGAS, NV - SEPTEMBER 22: Casey Cott attends the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Tara Ziemba/FilmMagic)
LAS VEGAS, NV - SEPTEMBER 21: Childish Gambino performs onstage during the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by Kevin Winter/Getty Images for iHeartMedia)
LAS VEGAS, NV - SEPTEMBER 21: Justin Jesso attends the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by JB Lacroix/WireImage)
LAS VEGAS, NV - SEPTEMBER 21: Ken Jeong poses in the press room during the iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by David Becker/Getty Images for iHeartMedia)
LAS VEGAS, NV - SEPTEMBER 21: Jack White attends the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by Gabe Ginsberg/Getty Images for iHeartMedia)
LAS VEGAS, NV - SEPTEMBER 21: Alyssa Edwards poses in the press room during the iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by David Becker/Getty Images for iHeartMedia)
LAS VEGAS, NV - SEPTEMBER 21: Jason Aldean attends the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by Tara Ziemba/FilmMagic)
LAS VEGAS, NV - SEPTEMBER 21: Montana Tucker poses in the press room during the iHeartRadio Music Festival at T-Mobile Arena on September 21, 2018 in Las Vegas, Nevada. (Photo by David Becker/Getty Images for iHeartMedia)
LAS VEGAS, NV - SEPTEMBER 22: Shanina Shaik attends the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by JB Lacroix/WireImage)
LAS VEGAS, NV - SEPTEMBER 22: Ashley Iaconetti and Jared Haibon attend the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Tara Ziemba/FilmMagic)
LAS VEGAS, NV - SEPTEMBER 22: Debby Ryan attends the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by JB Lacroix/WireImage)
LAS VEGAS, NV - SEPTEMBER 22: Logic attends the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Tara Ziemba/FilmMagic)
LAS VEGAS, NV - SEPTEMBER 22: (L-R) Boyz II Men, Nathan Morris, Wanya Morris and Shawn Stockman attend the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Tara Ziemba/FilmMagic)
LAS VEGAS, NV - SEPTEMBER 22: (L-R) The Vamps, Tristan Evans, Connor Ball, Bradley Simpson and James McVey pose in the press room during the iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Tara Ziemba/FilmMagic)
LAS VEGAS, NV - SEPTEMBER 22: Dustin Lynch poses in the press room during the iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Tara Ziemba/FilmMagic)
LAS VEGAS, NV - SEPTEMBER 22: Ryan Tedder attends the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Tara Ziemba/FilmMagic)
LAS VEGAS, NV - SEPTEMBER 22: James Maslow (L) and Dean Michael Unglert attend the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Kevin Mazur/Getty Images for iHeartMedia)
LAS VEGAS, NV - SEPTEMBER 22: Dan Reynolds of Imagine Dragons performs onstage during the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Ethan Miller/WireImage)
LAS VEGAS, NV - SEPTEMBER 22: Sabrina Carpenter attends the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Tara Ziemba/FilmMagic)
LAS VEGAS, NV - SEPTEMBER 22: Ryan Seacrest (L) and Kristin Cavallari speak onstage during the 2018 iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Kevin Mazur/Getty Images for iHeartMedia)
LAS VEGAS, NV - SEPTEMBER 22: Taran Killam attends the iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Sam Wasson/Getty Images for iHeartMedia)
LAS VEGAS, NV - SEPTEMBER 22: Kristin Cavallari poses in the press room during the iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Tara Ziemba/FilmMagic)
LAS VEGAS, NV - SEPTEMBER 22: Luke Bryan attends the iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Sam Wasson/Getty Images for iHeartMedia)
LAS VEGAS, NV - SEPTEMBER 22: (L-R) KJ Apa, Casey Cott, Luke Perry, and Skeet Ulrich attend the iHeartRadio Music Festival at T-Mobile Arena on September 22, 2018 in Las Vegas, Nevada. (Photo by Sam Wasson/Getty Images for iHeartMedia)
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On Saturday night, Justin Timberlake and Shawn Mendes took the stage -- at one point, together! -- as did Kelly Clarkson and Carrie Underwood. Other stars there on the second night of the 2018 iHeartRadio Music Festival were the Bellas, K.J.Apa and more of the stars of "Riverdale" and Kristin Cavallari.

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