Ariana and Sean looked every inch the loved-up couple as they put on a very public PDA for photographers at the prestigious music ceremony, which was held at the Staples Centre in Los Angeles.
Ariana rocked a thigh-split white and silver Versace frock, while rapper Sean looked smart in a black suit.
Ariana was also preparing for her first ever Grammy performance, and after the show, she took to Twitter to thank her beau.
"Thanks to my boyfriend for making me laugh through the nerves, unbearably awkward red carpet interviews," she said. "There is nothing weirder. I love you."
Ariana stripped it back for her Grammy performance and took to the stage to sing power ballad, 'Just a Little Bit of Your Heart', which was co-written by One Direction's Harry Styles.
Proud boyfriend Sean later wrote on Twitter: "Ari killed that s**t today! I love u baby, congrats."
Ariana earned two nominations at this year's Grammys. Her 2014 album My Everything was nominated for Best Pop Vocal Album, while her collaborative single 'Bang Bang' with Jessie J and Nicki Minaj was nominated for Best Pop Duo/Group Performance.
Last month, Sean opened up about his romance with Ariana, describing their relationship as "special".
'Too Fake' rapper Sean told Complex magazine: "We started as friends. I'd never done that. Usually you meet a girl and then start dating. We always saw each other in the studio, and we'd talk about songs we were working on.
"It was cool to have a girl that I could talk to about my problems. This is something special and I appreciate every moment of it."
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Grammys 2015 red carpet:
Copyright: Rex Features Picture Perfect