Kim Kardashian has poured her heart out in a birthday tribute to her “queen” sister Kourtney Kardashian.

The Skims founder reminisced about her shared experiences and cherished memories with the Lemme founder that they've built over four decades.

Taking to Instagram on Thursday, Kim shared a photo featuring Kourtney and Khloe, enjoying a splendid moment at the beach from her last trip.

She captioned the post, “Happy Birthday Queen @kourtneykardash There’s no one on this planet that I have spent more time with and have all of the same memories with growing up than you and I cherish them all.”

While reflecting on her bond with the Kourtney, Kim added, “Sharing a room and friends and cars and our lives together for four decades has been the most magical journey to have you by my side.”

The SKKN founder showered her love, noted, “I love you and I can’t wait for another 45 years together! I will especially cherish this last sister trip where all of our kids had dance parties til they passed out, the way we all did growing up!”

She capped off the caption, “Celebrating you today and grateful to you forever for always giving the best advice a sister could possibly give!”

On Kim’s heartfelt birthday post, Kourtney replied in the comment, “This caption I love you sooooo and so grateful for all of the incredible memories we have together… when I think it, it’s like a movie plays in my head of all of them! So blessed!”