The singer, 31, and the Broadway actor, 32, star in the highly-anticipated film adaptation of the Broadway musical and began dating after meeting on the set of the film in London nearly two years ago.
The couple has faced romance rumors when they went public with their romance shortly after their respective divorces in 2023.
Grande has praised her “amazing” and “adorable” boyfriend while promoting Wicked, which hits cinemas on November 22, despite claims that producers feared her romance with Slater would “overshadow” the film.
And her love for Slater was on full display Thursday as they shared a warm embrace in front of a sea of red carpet photographers at New York’s historic Museum of Modern Art.
Grande, wearing a glamorous strapless pink gown, got close to the Spamalot star as he posed for photos with co-star Bowen Yang.
The Dangerous Woman singer first took Slater’s hand before hugging him.
Slater could barely contain his smile during the sweet moment with his pop star girlfriend.
The actor, who plays munchkin Boq in Wicked, had one hand on Grande’s tiny waist while the other gripped her slim arm.
Grande did not arrive at the premiere with Slater, but instead arrived arm in arm with her Wicked co-star Cynthia Erivo.
Grande and Erivo channeled their characters Glinda and Elphaba, respectively, with their stunning looks on the red carpet.
Grande looked phenomenal in a pink satin peplum dress with an elegant sweetheart neckline.
The 31-year-old former Nickelodeon star, who has raised eyebrows over her appearance, accessorized with a diamond choker and matching earrings.
Her golden blonde hair, which she dyed to play the cheerful blonde Glinda the Good, was styled in an elegant bun.
Grande sported her favorite winged eyeliner and false lashes, which her makeup artist paired with a glossy nude lip.
Her boyfriend Ethan arrived at the red carpet event moments after her in a dapper navy suit.
His jacket had black lapels that matched the thin black tie secured around the collar of his white button-down shirt.
Grande hugged co-star Erivo tight, who put a glamorous spin on Elphaba’s iconic black gown.
The Tony Award winner, 37, modeled a flowing black gown with a sexy sheer bodice that showed off her cleavage.
She wore a black pearl choker around her neck and, as another nod to the Wicked Witch of the West, sported bright green eyeshadow.
Erivo wore a black net veil over her shaved head and eagerly showed off her dramatic fake nails, which were adorned with silver decals and green jewels.
In a recent interview, Erivo said she “gained a sister” in her co-star Grande after they bonded while filming Wicked.
“I’ve gained a sister. We talk almost every day at this point. We were both blown away by the connection we made right away,” Erivo told ELLE of her close friendship with Grande.
“I remember the first day we met. It was at Jon M. Chu’s [director] house and Stephen Schwartz [who wrote the music and lyrics for Wicked for both the original Broadway musical and the film] was there.
“He played a few songs for us and we sang together for the first time. It worked. It’s a very intimate thing to sing with someone. It’s a really beautiful dance: I have to follow you, you have to follow me.”
“It was one of the most gratifying things to know that there was someone so open and available, because she was, and that meant I could be, too.
“We also had a beautiful relationship off-screen. We had really beautiful conversations, some of which weren’t easy, but that’s what makes relationships like that.”
“Those difficult conversations you can have with someone that involve you having to be vulnerable are the things that bring you closer.”
Grande, Erivo and Slater weren’t the only Wicked stars and celebrities who graced Thursday night’s lavish red carpet soiree.
Bridgerton hunk Jonathan Bailey, who plays Elphaba’s love interest Fiyero Tigelaar, had viewers swooning as he posed in a sparkling white tuxedo jacket and fitted black trousers.
Jeff Goldblum, 72, who plays the Wizard of Oz, looked dapper in a black suit, dress shirt and tie as he snuggled up to his wife of 10 years, Emilie Livingston.
The 41-year-old dazzled alongside her famous husband in a stunning sleeveless black short dress and black stilettos.
Kristin Chenoweth, who originated the role of Glinda in Broadway’s Wicked in 2003, also appeared to support the upcoming two-part film.
The 56-year-old Tony Award nominee looked incredible as she flaunted her toned, tanned legs in a white blazer dress with a bedazzled collar.
Her signature blonde hair was worn straight and sleek and she added height to her petite 1.40m frame by donning a pair of strappy silver heels.
Glee star Lea Michele, whose version of Wicked’s Defying Gravity on the hit Fox TV show is iconic, exuded elegance in a sleeveless baby pink silk gown.
The outing comes less than three months after the 38-year-old actress gave birth to her second child, Emery, with husband Zandy Reich, 41. The couple welcomed their little girl on August 25.
And Michele proudly showed off her slim post-baby body during Thursday’s star-studded premiere.
She strolled through the Museum of Modern Art in pink ballet flats and her brown hair pulled back into an elegant bun.
SNL star Bowen Yang, who appears as Pfannee in Wicked, wore a classic black blazer over a white mesh blouse adorned with colorful 3D floral decals.
The upcoming two-part feature film is an adaptation of the long-running Broadway musical and is a prequel to The Wizard of Oz.
The film is set to hit theaters with release dates of November 22, 2024 for Wicked: Part One, and November 26, 2025 for Wicked: Part Two.
The cast of Wicked have embarked on a week-long press tour that included premieres in Sydney and Los Angeles.
The cast and crew of the film will soon be flying to the UK for the London premiere on November 18.