Taylor, 29, looked stunning in a light purple, sequin romper that elegantly showed off her slender, long legs. The "Gorgeous" singer added a pair of silver stilettos and pulled her hair back into a loose ponytail.
Halsey, 24, rocked a tuxedo ensemble, which consisted of a white asymmetrical button down shirt, black pants, a black bow-tie and pointed black heels.
John, 40, looked dapper in a lavender suit that he paired with a crisp white button down shirt and matching dress shoes.
Alicia Keys opted to wear a black, classic, off-the-shoulder jumper that she wore with a purple toned head scarf.
Shameless actress Jessica Szohr made jaws drop in a black body suit ensemble, which she paired with black see-through, bell-bottom pants and platform heels.
Madison Beer showed up to the awards show wearing a flawless white, strapless gown. The "Hurts Like Hell" singer accessorized with gold hoop earrings, pearl colored pumps and kept her brunette hair down.
Bebe Rexha rocked a contemporary look which consisted of a black top hat and a sexy deep-V black jumper. She added a pair of black heels and kept her blonde hair pulled back into a sleek ponytail.
Fashionista Heidi Klum attended the event in a loose fitted, cheetah print dress and impressively high matching boots.
The Vampire Diaries alum Kat Graham kept things simple but glamorous by wearing a white tee tucked into a pair of high-waisted black leather pants.
Maren Morris looked great in a multi-colored bejeweled mini dress that she wore with silver platform stilettos.
Zara Larsson was all smiles in a pastel floral romper. The "Ruin My Life" singer added a pair of silver heels and wore a simple diamond necklace.
Miguel and his wife Nazanin Mandi looked great! The "Sky Walker" singer wore a grey plaid suit with a neon green shirt and black shoes. His wife matched her man in a black and neon green pantsuit.
Elle Fanning kept things elegant at the award show and wore a light pink gown while keeping her blonde locks styled straight.
The Backstreet Boys made an appearance and even performed a medley of their most popular hits at the show.
Whose outfit from the 2019 iHeartRadio Music Awards show do you like best? Let us know in the comments below!