Must-See Star Sightings: December 16-31, 2018

The pop diva got all glammed up for her New Year's Eve performance at Nikki Beach Saint Barth. After singing, she rang in the new year by watching the fireworks display with her boyfriend, Bryan Tanaka (not pictured).

Keeping cozy in an oversized white turtleneck sweater, the "Wolves" singer carried a to-go container after grabbing lunch with a friend on Dec. 31. Earlier in the day, Gomez got in her last workout of 2018 with a hot Pilates class.

We'll never be the same after seeing the "Havana" singer hit the stage in Los Angeles for Dick Clark's New Year's Rockin' Eve With Ryan Seacrest 2019 on Dec. 31.

It may have been raining, but Xtina was still a queen of winter wonderland while performing a medley of her hits from NYC's Times Square during the same New Year's Eve 2019 celebration.

The trio rang in 2019 by partying with pals at the JEWEL Nightclub at ARIA Resort & Casino on Dec. 31. At one point in the evening, Rose even joined Tyga and his crew inside the DJ booth and Jordan hopped onstage for a shout-out.

Lean back! The "God's Plan" rapper looked like he was feeling fine while hosting the Mod Sèlection Champagne New Year's Party with John Terzian at Delilah in Los Angeles on Dec. 31.

The singer didn't let the rainy weather get in the way of his soundcheck as he prepared to perform "Brand New Day" in New York City's Times Square on Dec. 31. 

The "Blurred Lines" singer was all smiles as he posed on the red carpet at APEX Social Club at Palms Casino Resort in Las Vegas, Nevada, on Dec. 30. 

The reality star was hard to miss on the slopes as she donned a hot pink Prada snow suit while skiing with sister Kendall Jenner in Aspen, Colorado, on Dec. 29. 

The cute couple got playful for the camera at the grand opening of the first U.S. location of Mott 32, one of Hong Kong's most award-winning restaurants, at The Palazzo at The Venetian Resort in Las Vegas, Nevada, on Dec. 28. 

The American Idol alum kept the party going after the opening night of Lady Gaga's Las Vegas residency, Enigma, at Park MGM's Park Theater, as he and other celebs flocked to the official after-party at Houston Hospitality's new speakeasy and club, On The Record. 

The pair were all smiles as they attended the Dick Clark's New Year's Rockin' Eve press junket held at Times Square in NYC on Dec. 28.

The Jersey Shore Family Vacation star got the crowd hyped up during his sold-out show at Marquee in New York City on Dec. 28.

Casually dressed in a white tee, brown jacket and jeans, the singer was spotted out in Los Angeles on Dec. 27.

The couple was one fashionable duo as they were spotted grabbing coffee in Los Angeles on Dec. 26. 

The Fab Four couldn't have looked more stylish as they stepped out for Christmas Day services at the Church of St. Mary Magdalene at Sandringham on Dec. 25. 

The Twilight star was spotted out and about with her rumored new flame, stylist Sara Dinkin, in Los Angeles on Dec. 24, a few days after reports surfaced that Stewart and Victoria's Secret model Stella Maxwell had broken up.

The singer-model-reality looked stunning in a chic and sexy black velvet backless gown while stepping out of her new, luxurious Rolls-Royce Dawn outside of the trendy West Hollywood seafood eatery Catch in the early hours of Dec. 23.

The "Your Love Is My Drug" singer rocked a ripped white tee, jeans and a furry pink and aqua coat while spotted at the Los Angeles airport on Dec. 22.

Rocking a fun red sequined number, the "I Like It" rapper was all smiles while performing in the Electric Holiday Concert in San Juan, Puerto Rico, on Dec. 21.

The actor performed a Haka dance during a screening of Aquaman in Honolulu, Hawaii, on Dec. 21.

Days after leaving a mental health facility, the "Back to You" singer was spotted running errands with friends in downtown Los Angeles on Dec. 21.

Pretty as a peach! J.Lo was all smiles while shopping in Beverly Hills in a comfy, all-pink outfit on Dec. 20.

Lookin' good! The Queer Eye star turned the sidewalk into a runway as he sashayed down the streets of Los Angeles on Dec. 20.

The "IDGAF" singer was a smiley siren during her set at Ellie Goulding's Streets of London charity show in England's capital city on Dec. 20.

The lovebirds looked more smitten with each other than ever at their third wedding reception in Mumbai, India, on Dec. 20.

Mrs. Bieber sported a rocker tee, pale yellow sweatpants and white "ugly" sneakers during her day out in Los Angeles on Dec. 20.

Gyllenhaal supported his friend at a special screening of her new film, Vice, in New York City on Dec. 20.

The Bumblebee star goofed around while visiting the Empire State Building in NYC on Dec. 20.

Sporting a spiky 'do, the Lizzie star did a little shopping in Los Angeles on Dec. 20.

The Bumblebee star made a major sartorial statement outside a New York City radio station on Dec. 20 in a floral dress and matching thigh-high boots topped with a maroon fur-lined coat and colorful boxed handbag.

All tied up with a bow! The "For You" singer's black-and-white dress was a present for all of us, and she paired the mod mini with sheer black tights, peep-toe tie-ankle platforms and oval sunglasses during a day out in Paris, France, on Dec. 20.

How lucky is Gwen Stefani? The country singer performed his latest single, "Turnin' Me On," on The Ellen DeGeneres Show on Dec. 20.

The Game of Thrones star stocked up on holiday cards while shopping in NYC's SoHo neighborhood on Dec. 20.

Looking sleek in a silky all-black ensemble, the reality star was still rocking slightly pink tresses while shopping for baby clothes with her sisters in Sherman Oaks, California, on Dec. 19.

Pop goes the actress! The When Calls the Heart star proved she's still a kid at heart, blowing a giant bubble and throwing up peace signs during a chewing gum-filled visit to Hallmark's Home & Family in Universal City, California, on Dec. 19.

The mom of three was in a joyful mood while out for a walk with a friend in Los Angeles on Dec. 19.

Even Deadpool carries his own stuff! Reynolds was spotted with both his backpack and jacket in hand while out in New York City on Dec. 19.

The former first lady looked amazing in a yellow dress and glittery boots when she sat down with the Sex and the City actress to discuss her new book, Becoming, at the Barclays Center in Brooklyn, New York,  on Dec. 19.

After a quick trip to New York, Jonas held onto his wife's hand during their second wedding reception at JW Marriott in Mumbai, India, on Dec. 19.

The newlywed had the blues -- in the best possible way -- as she picked up an iced coffee from Blue Bottle in Beverly Hills on Dec. 19.

The indie screen queen struck a fierce pose at the Saint Laurent's 50th-anniversary screening of Belle de Jour at NYC's Museum of Modern Art on Dec. 19.

The Mary Poppins Returns star had his mouthful while filming a segment for Despierta America in Miami, Florida, on Dec. 19. 

A joyous lady during a joyous season! The Vice actress was in a jolly mood outside the Build Studio in New York City on Dec. 19.

Bach, Noel and Pharoah came out to support Duke at an intimate dinner at The Restaurant at Montage Beverly Hills on Dec. 19, where the Black Panther actor was celebrated as a 2018 breakout star by MCM and GQ Magazine. 

Coffee queen! The Pretty Little Liars alum got her caffeine fix in on Dec. 19, making her usual morning run to Starbucks in Studio City, California.

Rocking a black-and-white mesh dress, lace-up black heels and oversized shades, the hotel heiress stopped to pose for photogs before doing press in New York City on Dec. 19.

Air five! The Foo Fighters frontman showed fans some love as he made his way onto Jimmy Kimmel Live's L.A. set on Dec. 18.

The Welcome to Marwen star snapped pics with fans while also visiting Jimmy Kimmel Live.

Happy birthday, Katie! The Dawson's Creek alum was draped in a rainbow-hued long cardigan as she made her way to Serendipity in New York City to celebrate the big 4-0 on Dec. 18.

The 22-year-old actress kept warm by layering her navy blue jumpsuit with a long silver puffer after her appearance on the Today show in New York City on Dec. 18.

The pregnant duchess cradled her baby bump while talking to folks outside the Brinsworth House in Twickenham, England, on Dec. 18, where she was bringing holiday cheer to the Royal Variety residential nursing and care home.

As fans stood anxiously waiting behind him, the superhero actor snapped a selfie on the blue carpet at the Australian premiere of Aquaman in the country's Gold Coast on Dec. 18.

The festively dressed actress got some holiday shopping done in Los Angeles on Dec. 18.

Who knew a puffy jacket could look this chic? The British singer's wore a wintertime separates set -- a plaid cropped cape coat and ankle-length pencil skirt -- with a navy blue sweater, black knee-high boots and tiny oval sunglasses while out in New York City's SoHo neighborhood on Dec. 18.

Meow! The celebrity trainer looked fierce in a black turtleneck, leopard-print pencil skirt and T-strap black heels at Build Studio in New York City on Dec. 18.

J.Lo's maroon beanie matched her beau's sweater as the lovebirds walked hand in hand after a meeting in Beverly Hills on Dec. 17.

The stunning women bonded at the American Ballet Theatre's Annual Holiday Benefit in Beverly Hills on Dec. 17.

The co-stars shared a laugh at a Cinema Society-hosted Mary Poppins Returns screening in New York City on Dec. 17.

The reality star paired her abs-baring all-black ensemble with an artsy gold choker for dinner at Sugarfish Sushi in Calabasas, California, on Dec. 17.

The Bird Box star was anything but mellow yellow as she arrived to The Late Show with Stephen Colbert set in New York City in a bright fur coat and thigh-high black stiletto boots.

Pretty in pink! The Dirty John star held court onstage during Tribeca Talks: The Journey, sponsored by TUMI, at Andaz West Hollywood on Dec. 17.

She's watching you! The Mary Queen of Scots star rocked a spooky cat-eye sweater and matching gray tea-length skirt to the SiriusXM Studios in New York City on Dec. 17.

The 25-year-old actress posed next to her PIMP movie poster at an NAACP Image Awards screening of the film in Los Angeles on Dec. 17.

We were green with envy after seeing Blunt look so chipper outside of the Good Morning America set in New York City on Dec. 17.

The "Girls" singer looked like a goth princess in one of quite a few looks she donned over the course of a busy workday in New York City on Dec. 17.

Flower power! The British actress looked prim and proper at her "A Life in Pictures" BAFTA event photocall in London, England, on Dec. 17.

The A Faithful Man actress signed autographs for fans outside the C a Vous TV station in Paris, France, on Dec. 17.

The "Chains" singer loaded up on winter gear after a shopping spree at Burton in NYC's SoHo neighborhood on Dec. 16.

The co-stars cleaned up nicely for a screening of their new film, On the Basis of Sex, in New York City on Dec. 16.

Dressed in his best winter flannel, the actor-director spoke about his film, A Quiet Place, during a MoMa's Contenders Screening in New York City on Dec. 16. 

Pucker up! The "I'm a Mess" singer blew a kiss backstage at Y100 Miami's Jingle Ball 2018 in Sunrise, Florida, on Dec. 16.

The husband-and-wife duo-- who perform professionally as Ashlee + Evan -- performed together during Mercedes in the Morning's Not So Silent 2018 show at the Joint inside the Hard Rock Hotel & Casino in Las Vegas, Nevada, on Dec. 16.

Shortly before earning the top tiara, Miss Philippines linked arms with Ne-Yo as the singer performed at the 2018 Miss Universe Pageant in Bangkok, Thailand, on Dec. 17. 

The music icon performed live at a sold-out show at the O2 Arena in London, England, on Dec. 16, as part of his Freshen Up world tour.