Paris Hilton Celebrates Britney Spears' 42nd Birthday: 'Keep Shining Sis'

"Sending you lots of love on your special day!" Hilton wrote to Spears

Paris Hilton is celebrating Britney Spears on her 42nd birthday!

The businesswoman, 42, paid tribute to the singer with a post shared on Instagram Saturday marking the special occasion.

"Happy Birthday @BritneySpears 👑," Hilton began the caption of her post. "So many fun memories together👯‍♀️."

"Love you so much🥰 Sending you lots of love on your special day!" she continued. "🩷 Keep shining sis💫."

Alongside her sweet message, Hilton also shared a series of photographs of herself and Britney from throughout the years, including images from nights out on the town, as well as shots from behind the scenes at awards shows.

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Related: Paris Hilton Says She's 'So Proud' of Britney Spears for 'Telling Her Story' in New Memoir (Exclusive)

Hilton and Britney have been friends for years and have long supported each other publicly.

Ahead of the release of the "Stronger" singer's memoir, The Woman in Me, Hilton told PEOPLE she was "so proud" of Britney "for telling her story."

"I know how hard it can be doing a memoir because you have to really dive in and think about so many moments in your life that I'm sure you don't even want to think about," she explained. "But it is truly such a healing experience, and writing my book, [Paris: The Memoir], has changed my life in so many ways,"

Added Hilton: "I'm really hoping that she feels the same way with this. I am just proud of what a strong woman she is."

Related: Britney Spears Rings in Her Birthday with Her Mother and Brother: 'A Really Nice Moment for the Family' (Source)

Britney celebrated turning 42 with a party in Los Angeles on Friday night, which PEOPLE confirmed was attended by her mother Lynne Spears and brother Bryan Spears.

“Being together and celebrating her birthday was a really nice moment for the family," a source said.

Photos obtained by TMZ showed Lynne, 68, leaving the party venue on Saturday morning, seemingly after spending the night there following the event.

Her attendance at Britney's birthday celebration took place after the pop star shared in May that the two had repaired their fractured relationship.

In an Instagram post at the time, Britney revealed that her mom had recently visited her house for the first time in years.

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