attends Paris Hilton's 39th birthday party with sister Kourtney ...

and Paris Hilton have a friendship that dates back to childhood.

And with so much history between the two, it's no wonder that the Keeping Up With The Kardashian's star stepped out on Thursday evening to ring in Hilton's 39th birthday with the DJ in Los Angeles.

Kim was joined by sister Kourtney Kardashian at the 'Sliving' themed soiree that featured appearances by Hilton's family members as well as a slew of other famous faces.

Celebration: Kim Kardashian (left) attended longtime friend Paris Hilton's 39th birthday party with sister Kourtney Kardashian (right) on Thursday evening

Celebration: (left) attended longtime friend Paris Hilton's 39th birthday party with sister Kourtney Kardashian (right) on Thursday evening

Interesting choice: The 39-year-old reality star stepped out for the star-studded soiree in a curious combo that featured snakeskin pants and an oversize royal blue hoodie

Interesting choice: The 39-year-old reality star stepped out for the star-studded soiree in a curious combo that featured snakeskin pants and an oversize royal blue hoodie

Interesting choice: The 39-year-old reality star stepped out for the star-studded soiree in a curious combo that featured snakeskin pants and an oversize royal blue hoodie

Sisters on social: On their way home from the celebration, Kim took to Instagram to share a short clip of herself and Kourtney posing in the backseat of a luxury vehicle

Sisters on social: On their way home from the celebration, Kim took to Instagram to share a short clip of herself and Kourtney posing in the backseat of a luxury vehicle

Kardashian kept it low-key for Hilton's bash in an oversize blue hoodie, which she styled with a pair of figure-hugging snakeskin pants and coordinating shoes.

Her signature brunette tresses were pulled up and slicked back into a bun that stemmed from a neat middle part.

The SKIMS creator opted for a sultry brown smokey and a bronzed complexion that was finished off with a swipe of peachy nude lipstick.

Kourtney donned the same hoodie as her sibling, but in a black variation.

Happy Birthday Paris! The now 39-year-old star graced her party guests in a stunning silver dress that glistened in every direction

Happy Birthday Paris! The now 39-year-old star graced her party guests in a stunning silver dress that glistened in every direction

Barbie girl: The heiress has numerous cakes, but one cake in particular featured a major nod to her 'sliving' theme as well as her love of Barbie

Barbie girl: The heiress has numerous cakes, but one cake in particular featured a major nod to her 'sliving' theme as well as her love of Barbie

Barbie girl: The heiress has numerous cakes, but one cake in particular featured a major nod to her 'sliving' theme as well as her love of Barbie

Kim shared a short video clip of the pair leaving the exclusive party to her Instagram page, which showcased the sisters posing in the back of a luxury vehicle.

Earlier in the evening, Kardashian made sure to provide her 160million followers with some behind the scenes footage from inside Hilton's over-the-top mid-week celebration.

'Sliving,' a slang term penned by Paris that combines the words 'slaying' and 'living,' was the night's theme and the hotel heiress made sure it was drilled into the eyes of all those in attendance.

Her Prince: Paris shared a tender moment with her entrepreneur boyfriend Carter Reum (right)

Her Prince: Paris shared a tender moment with her entrepreneur boyfriend Carter Reum (right)

Her Prince: Paris shared a tender moment with her entrepreneur boyfriend Carter Reum (right)

Unusual pair: Chris Brown showed up to Hilton's birthday party in an eye-catching Supreme jacket that featured a menacing skull and flames

Unusual pair: Chris Brown showed up to Hilton's birthday party in an eye-catching Supreme jacket that featured a menacing skull and flames

Partying it up: The Look At Me Now singer could be seen making his way through the pink-lit party on Thursday night

Partying it up: The Look At Me Now singer could be seen making his way through the pink-lit party on Thursday night

Sisterly support: Paris' little sister Nicky Hilton, 36, rolled up to the party in a stunning metallic leopard print dress paired with studded black heels

Sisterly support: Paris' little sister Nicky Hilton, 36, rolled up to the party in a stunning metallic leopard print dress paired with studded black heels

All together now: Paris and Nicky seem inside the party with a friend

All together now: Paris and Nicky seem inside the party with a friend

Those entering the party were greeted by a 'Slivington Manor' neon sign that glowed in Paris' favorite color.  

The unique theme was embraced further through the use of a 'sliving' Instagram filter created specifically for the now 39-year-old, as well as a custom technicolor BMW that guests could pose with.

The Simple Life star was treated to two birthday cakes, one decorated in a barrage of Barbie and another dressed more simply in white and red icing that read 'Happy Birthday Paris.'  

Proud mom: Mother Kathy Hilton was not going to miss her daughter's epic celebration

Proud mom: Mother Kathy Hilton was not going to miss her daughter's epic celebration

Mommy and me: Rocking her party's custom Instagram filter, Paris posed with her mother Kathy Hilton (left) inside the venue

Mommy and me: Rocking her party's custom Instagram filter, Paris posed with her mother Kathy Hilton (left) inside the venue

Sister Nicky was in charge of presenting Paris with her first cake, which would require the Simple Life star to make her big birthday wish.

The stunning siblings later danced upon a marble table top, after Paris had grabbed a microphone to address her party's crowd. 

Hilton documented all of her birthday shenanigans on her Instagram page, which included an array of gorgeous seflies, as well as videos of the party's ambiance.   

Hand-in-hand: Supermodel Heidi Klum (left) was fashionably fluffy in a tweed jacket, as she walked hand-in-hand with her husband Tom Kaulitz (right)

Hand-in-hand: Supermodel Heidi Klum

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