The singer wore a long black sequin Saint Laurent gown with a deep, plunging neckline and loose, tousled waves in her hair while Hemsworth sported a classic tuxedo.
This was one of the couple's first public appearances since getting married in December after a decade-long love story.
Earlier this month, Cyrus walked the red carpet at the "Isn't It Romantic" premiere in her new husband's place while Hemsworth was dealing with undisclosed health issues.
Hemsworth's co-star in the upcoming romantic comedy and fellow newlywed Priyanka Chopra Jonas was also in attendance at the Vanity Fair party Sunday night with her husband, Nick Jonas.
That pair, who tied the knot in November in India, shared a sweet embrace while they waited in line to take an official portrait at the event.
Taking a decidedly different style approach, Melissa McCarthy and Ben Falcone, who have been married for over a decade, wore matching Adidas tracksuits to the star-studded post-awards party.
The "Can You Ever Forgive Me" actress stepped out in a stylish black and white pantsuit at the awards ceremony earlier in the evening.
EGOT winner John Legend and wife Chrissy Teigen were also in attendance and posed for a photo together before the mother of two jokingly pushed him aside for a solo shot on the "very important carpet."
Singer Jennifer Lopez and boyfriend Alex Rodriguez did a quick change and arrived at the after-party in another glamorous outfit that almost upstaged their Oscars red carpet look.
For the party, J.Lo wore an iridescent midnight blue gown with fan detailing that showed some skin with a thigh-high slit and kept her hair down in big loose curls.
"Aquaman" star Jason Momoa and his wife and actress Lisa Bonet looked pretty in pink on Sunday.
Momoa turned heads when he went shirtless at the party in a custom-made Karl Lagerfeld blush pink velvet tuxedo that he wore in honor of the German designer who died last week. Bonet wore a matching couture dress from Lagerfeld's last Fendi collection.
British actress Sophie Turner and her fiance Joe Jonas also appeared at the event. The "Game of Thrones" star wore a gold sequin gown with black underlay and tiered wrap ruffles, while the singer sported an off-white tux.
"Oceans 8" and "Bird Box" star Sarah Paulson arrived in a puffy hot pink dress with midriff cut-outs alongside her girlfriend of over three years, actress Holland Taylor.
Jeff Goldblum, 66, and his wife Emilie Livingston, 36, embraced on the Vanity Fair carpet in chic black and white outfits.
Actress Leslie Mann stunned in an off-white gown covered in feathers and beading next to her filmmaker husband of 21 years, Judd Apatow. The cute Hollywood couple, who have collaborated on comedies like "Knocked Up," were all smiles together at the after-party.