Tristan Thompson is celebrating his “best friend” Khloé Kardashian.

The Cleveland Cavaliers player, 33, penned a touching tribute to Kardashian as she celebrated her 40th birthday on Thursday.

Posting several slides on his Instagram Stories, Thompson wrote, “Happy Birthday Khloé!!” and “You are my best friend” on one slide.

Tristan Thompson IG screenshot

Tristan Thompson wished his ex, Khloé Kardashian, a happy birthday on Thursday, calling her his “best friend.”Instagram/realtristan13

Tristan Thompson Khloe Kardashian True selfie
He also called her “the best mom” and shared a photo of Kardashian with their daughter, True, 6.Instagram

“You are the best mom,” he wrote on the following post which showed Kardashian posing with their daughter, True, 6.

Tristan, who also shares 1-year-old son Tatum with Kardashian, closed with a photo of the reality TV star and his younger brother, Amari — who has epilepsy and other medical conditions — calling her “the most incredible human being I’ve ever met.”

But they weren’t the only ones to wish Khloe a happy birthday.

Khloe Kardashian and Amari Thompson.
He closed his birthday tribute calling her “the most incredible human being.”Instagram/realtristan13

Tristan Thompson and son Tatum
Tristan also shares 1-year-old son, Tatum, with the “Kardashians” star.realtristan13/Instagram

After recently being involved in a heated conversation with Khloe on the latest “Kardashians” episode, Kim wished her sister a happy birthday with a sweet message online.

“Welcome to the f—ing 40 club baby!!!!! @khloekardashian I feel like you have been waiting for years to finally be done with your 30’s and the time has now come,” she said.

“I know this will be the best decade of your life filled with so much love and happiness! I’m so excited for you to experience this because I know how good it is, and no one deserves this more than you!”

“What a crazy life we live! I couldn’t do it without you by my side! Thanks for being the best friend and sister a girl could ever dream of. Happy Birthday,” Kim closed.

Khloe Kardashian selfie
Khloé’s sister Kim and mom, Kris Jenner, also wished her a happy birthday on Thursday.khloekardashian/Instagram

Khloé Kardashian, Dream Kardashian, True Thompson, Kris Jenner, and Amari Thompson.
“You are the most amazing daughter and have been the greatest gift in life,” Jenner wrote of Khloé on Instagram.khloekardashian/Instagram

Khloe’s mom, Kris Jenner, also delivered a lengthy note honoring her daughter on Instagram.

“You are one of the most wonderful loves of my life, and I cherish each and every glorious memory we have ever made. You are the most amazing daughter and have been the greatest gift in life, but watching you as a mommy has been so remarkable for me,” Jenner, 68, said along with a set of photos taken throughout Khloé’s life.

“You are such a joyful, happy, funny slice of life and when I’m with you, you always make me feel so special and so happy to be around you,” she continued.

“I love your strength and your sensitivity and your vulnerability and your support. Happy birthday, my beautiful girl and may all of your dreams come true. I love you beyond measure, more than I can ever explain in words, and you will always be my Bunny 🐰 love, Mommy.”