Here's every moment that went viral on Twitter throughout the night, sparking praise, shock and more than a few memes.
Taylor Swift Opens the Show
The hashtag MEonBBMAs was already trending before the show even started, as Taylor Swift's legion of fans got excited for the debut performance of her new single, "ME!"
The singer stayed true to the song's music video by keeping the visual's pastel palette for the performance, as Panic! at the Disco's Brendon Urie literally flew onto the stage to join her. As the song ended, the two flew over the audience on a massive umbrella, confetti exploding around them.
Among the moments that started trending was Swift's ex-boyfriend Joe Jonas watching the performance from the audience.
Clarkson kicked off the show by doing what she does best: singing other people's songs better than they do.
After Taylor's performance, the OG "American Idol" hit the stage with one amazing medley of hits from the last year, including "Meant to Be," "East Side, "Boo'd Up," "Girls Like You," "The Middle," "One Kiss," "Tequila" and "High Hopes."
She even rapped -- in Spanish -- to tackle "I Like It Like That" ... and paid tribute to Madonna with "Material Girl" and Mariah with "Touch My Body."
Imagine Dragons picked up the trophy for Top Rock Artist during the show, using their acceptance speech to make a strong statement against conversion therapy.
"I just want to take this moment to say there are still 34 states that have no laws banning conversion therapy. 34," said singer Dan Reynolds, who grew up in the Mormon church and is an advocate for gay Mormon youth.
"And on top of that, on top of that, 58 percent of our LGBTQ population live in those states. This can change," he continued. "This can change, but it's going to take all of us talking to our state legislation pushing forward laws to protect our LGBTQ youth. Lastly, I just want to say, we have seen what conversation therapy [does]; that our LGBTQ youth have double the rate of depression [and] triple the rate of suicide after conversation therapy. It's not working [and] needs to change."
I've been a stan of Imagine Dragons but now I'm starting to stan even more!!!! #BBMAS
South Korean boy band BTS was trending all night, basically any time the camera cut to them throughout the evening.
It started with their appearance on the red carpet and went even higher when they were seen during Kelly's opening medley and clapping for Halsey during her solo performance. The screams on the show went into overdrive when the group picked up the trophy for Top Duo/Group, a moment which also really popped on social media.
Then there was their performance of "Boy With Luv" with Halsey, which made both the audio audience and Twitter downright explode.
Nick, Joe and Kevin Jonas returned to the stage for the first time in over a decade for their debut performance of new single "Sucker."
Before they got to the hit, however, Nick kicked it off by singing his solo smash "Jealous." Brother Joe joined for part of that song, before the two launched into "Cake By the Ocean." Finally, Kevin popped up on stage and the trio was complete.
The crowd ate it up as the guys proved they still have it, with their significant others Priyanka Chopra, Sophie Turner and Danielle Jonas all rocking out in the audience.
Drake Spreads the Love
Picking up the trophy for Top Male Artist, Drake seemingly honored Nipsey Hussle and other artists we recently lost -- like Avicii, Mac Miller, XXXtentacion -- by telling the audience to let other musicians know they're loved while they're still around.
"We've obviously had an unfortunate series of losses within our business," said the rapper. "I just want to encourage everybody to let other artists know how you feel about them, let them know that you love and respect them while we're all still here."
After calling out Offset, he added, "To all of us, we put in a lot of work together, this is our thing, we gotta protect it. I just encourage you tonight to show somebody some love , tell somebody you love their music, you love what they do. That's it."
Madonna's Trippy (and Very Expensive) Performance
The Queen of Pop reportedly dropped $5 million on her performance of "Medellin" with Maluma on Wednesday. So, where did all the money go? Holograms of herself.
Throughout the song, four additional versions of Madame X teleported on and off screen, interacting with the very-real singers and dancers actually on stage. Not fake: Maluma's sex appeal as he danced alongside Madge.
Madonna delivered a unique performance while everyone else was doing some basic repeated shit, yet people drag her. For what? For trying new things and being interesting. I feel sorry for y'all. You're all a bunch of ageist people and nothing else. #BBMAs pic.twitter.com/W0lBW10Oc6
Before picking up her Icon Award, Mariah Carey performed a medley of her many, many, many hits. After starting with recent single "No," she really got the crowd -- including kids Moroccan and Monroe and Taylor Swift --going with "Always Be My Baby" and "Emotions." And, yes, she hit the whistle notes. It continued with "We Belong Together" and "Hero," before she hit the podium to grab her trophy.
After wiping tears from her eyes and throwing the tissue into the audience (GIFs below), she gave a shoutout to her twins and thanked Billboard for the honor. Acknowledging the "ups and down of my career" and the many memes she's sparked along the way, she gave special thanks to her fans, "who are unlike any other entity I have ever known. They have lifted me out of the depths of hell and brought me back with their devotion and love."
"To anyone who's ever told me that a song I wrote saved their life, I thank you, because you saved mine," she added.
Watch her performance below, then see some reactions.
Mariah Carey wiping her tears and throwing the tissue on the Billboard Music Awards stage is already iconic pic.twitter.com/XslM05mEU5
The night ended with one limber performance from Paula Abdul, who proved that she can still shake it like she did in the '80s at the age of 56.
Showing off her killer legs in a sparkly black leotard, the former "American Idol" judge danced her way through "Straight Up," "The Way That you Love Me," "Opposites Attract" -- with MC Skat Kat! -- "Cold Hearted Snake" and "Forever Your Girl."
The performance comes the same day she announced her upcoming Las Vegas residency at the Flamingo, kicking off August 13 and running select dates through January 2019.
Oh yeah, she also pelted Julianne Hough with her hat -- see that below!