Leonardo DiCaprio helped throw Rihanna a star-studded 27th birthday party in L.A. on Friday, Feb. 20, an insider exclusively tells Us Weekly -- get the details Credit: Tibrina Hobson/FilmMagic

A good time for RiRi!

Leonardo DiCaprio helped throw Rihanna a star-studded affair for her 27th birthday on Friday, Feb. 20, an insider exclusively reveals to Us Weekly. The shindig took place at a private home in Beverly Hills and went past 4 a.m. in the morning.

"There were balloons that spelled out her name set up," the source tells Us. The "FourFiveSeconds" singer dressed in a plunging dress and kept her dark locks down and slicked back.

Riri's day

A photo posted by Tommy Chiabra (@tommy_chiabra) on Feb 21, 2015 at 11:21am PST

Rihanna also was surprised with a leopard print three-tier cake. "Naomi Campbell was right next to her when she blew out the candles," the source says. Other famous faces in attendance included Mick Jagger, Beyonce, Jay Z, Russell Simmons, model Angela Martini, Tommy Chiabra, and Richie Akiva.

Last night ???? happy #Bday @badgalriri #rihanna #LA

A video posted by Angela Martini (@angela_martini) on Feb 21, 2015 at 12:07pm PST

As exclusively reported, Rihanna and DiCaprio, 40, recently spent Valentine's Day together. They've been meeting up for months, and continued the fun on her birthday. The insider adds: "They were dancing close all night."