Watch Rob Kardashian's Sweet Birthday Tribute From Khloe Kardashian's Kids True and Tatum Thompson

Rob Kardashian is a very lucky Uncle Bob!

The former reality star, who has stayed out of the spotlight in recent years, turned 37 March 17—St. Patrick's Day—and received a sweet and musical birthday tribute from his sister Khloe Kardashian's kids True Thompson, 5, and Tatum Thompson, 19 months.

In an Instagram video shared by the Good American founder, her daughter sings "Happy Birthday" to her "Uncle Bob" while standing in front of a closed window beside her brother and near the family's cat, Grey Kitty. Khloe then cheers while Tatum runs to her, then later says his uncle's name and claps.

The Kardashians star and other members of her family also shared heartwarming birthday messages to Rob.

"Robert I couldn't be prouder or more honored to say I am your sister," Khloe captioned her post, which also included throwback pics of the two. "I couldn't be prouder to be living life with you. I couldn't be luckier that I get to call you whenever I want about absolutely nothing. And the coolest part is, you actually answer the phone for me ha! I thank God every day for our relationship and the relationship that our children get to have."

Khloe also shared her hopes and dreams for her brother, dad to daughter Dream Kardashian, 7.

"Be the greatest person you can possibly be. Do things that make you proud. For you to have gratitude for even the smallest of things. Surround yourself with people who bring out the best of you. Believe in yourself and in your journey. Continue to be exactly who you are, loving, compassionate, caring, intelligent, respectful. Let go of the pressure that your past has put on you. Thrive at your own pace. Don't try to be perfect, Simply try to Be better than you were yesterday."

Khloe continued, "I love you Bobby boy! My bestie for the restie!!! You'll forever be my best Newsie 'open the gates and seize the day.'"

Kris Jenner also shared her own tribute to Rob. "You are the most incredible son a mother could ever ask for and one of the most loving, generous, kind, caring men I've ever known," she wrote on Instagram, alongside throwback pics of him. "You will never know how much of my heart you hold."

She added, "You are not only an amazing son but the world's best daddy to Dream, and she loves you so much!!!! It is such a joy to see you grow as a father with every year that goes by, and I hope you know how proud I am of you every single day."

Kourtney Kardashian and Kim Kardashian both also posted throwback pics of themselves with Rob in their own birthday tributes to him. "Happy Birthday to the sweetest funniest best brother in the world!" the SKIMS founder wrote. "@robkardashianofficial I love you so much and so blessed to have u as my brother!"

Kourtney commented, "The actual best brother in the world."

Look back at photos of Rob over the years:

Kris Jenner welcomed her only son and youngest child with Robert George Kardashian, named Robert Arthur Kardashian, on St. Patrick's Day in 1987.

Robert and Rob couldn't look more alike in this throwback snap.

A bleach-blonde Rob smiles from ear-to-ear for a photo with sister Kylie Jenner.

As you can see from this vintage pic, Rob and sister Khloe Kardashian have always been close.

Rob and Khloe pose for another sibling snap

Rob enjoys crystal clear water while abroad.

Rob joins mom Kris, sisters Kim and Khloe on the red carpet at the Kardashian Charity Knock Out at the Commerce Casino in November 2009.

For Kim's birthday in 2010, siblings Rob, Khloe and Kourtney hit up the TAO Nightclub with the birthday girl in Las Vegas.

Khloe supports brother Rob at the 2011 BBVA NBA All-Star Celebrity Game in Los Angeles, Calif.

The Keeping Up With the Kardashians alum plants a kiss on then-girlfriend Rita Ora.

Rob receives a sweet touch from Rita in this black-and-white photo.

Rob beams with pride in this solo shot from his Arthur George launch at Neiman Marcus.

Rob and sister Kim hit the red carpet at the World's Most Beautiful magazine launch event at Drai's Hollywood in August 2011.

The Keeping Up With the Kardashians siblings attend the E! 2012 Upfront in New York City.

Rob rings in his 26th birthday at the 1 OAK Nightclub at the Mirage in March 2013.

Rob enjoys a pulled pork sandwich in Malibu in this #tbt from 2015.

Khloe and Rob catch some Zzzs in this Instagram photo.

Kylie and Rob spend some quality time together.

After three months of dating, Rob and Blac Chyna announce their engagement on April 5, 2016.

Following their engagement, Rob and Chyna step out for his birthday at the Hard Rock Cafe in Hollywood on May 10, 2016.

In May 2016, Rob and Chyna announce they're expecting a baby together. The twosome reveal they are having a little girl in September 2016.

Rob and Chyna welcome daughter Dream Kardashian on November 10, 2016.

Rob shows love to his infant daughter Dream.

The father of one watches over his little one as he helps her float in the pool.

Dream looks comfortable in the water in this snap with her father.

Rob has mom Kris, known as Lovey to her grandchildren, spend quality time with baby Dream.

Dream's parents give her a magical day at Disney, including a moment with Minnie Mouse!

Dream can't stop giggle as dad Rob lifts her in the air.

The super private star proudly holds up his only child.

Dressed as a character from Trolls, Rob poses for a Halloween photo with mom Kris in 2019.