Selena Gomez continued her 21st birthday celebration with another big, star-studded party, where Justin Bieber made an appearance in Malibu on Saturday night, according to E! Online.

The "Birthday" singer, who turned 21 on July 22, hopped aboard a party bus with Nina Dobrev and Julianne Hough en route to a gyspy-themed soiree at the Revolve Beach House. However, the big news came when Bieber was caught arriving to the festivities, reported E!

The "Hearbreaker" crooner came in his cheetah-printed Audi R8, with a red rose in his hand to give to his ex-lady love.

Bieber jointed Jaden Smith and many other inside the venue to celebrate the "Spring Breakers" star on her milestone occasion.

Hough and Dobrev transformed themselves into gyspies, looking every inch the part with glitzy head scarves, bedazzled tops and baring their midriffs.

E!'s Sierra Marquina noted that the stars were having tons of fun, "Here's to being young, wild and free!"

And when the party ended around 2 a.m., Bieber got into the same car as the "Getaway" actress, who had already started her birthday with appearances at Hough's 25th birthday party in Los Angeles on July 20 and took some Jack Daniels whiskey shots as her first legal drink.

Gomez was also surprised by friends with a leopard print-frosted cake bearing Bieber's photo on July 20, according to Hollywood Life.

And according to a source, Gomez and her on- and off-again love spent the rest of the night at Bieber's Calabasas home after her immaculate shindig on Saturday.

For more birthday photos, click HERE.

Whether the reunion means the couple are back together again remains a mystery. Tell us what you think in the comments section below!