For Zayn Malik, his daughter Khai is a big part of the story of his life.

In fact, the One Direction alum considers the 4-year-old—who he shares with ex Gigi Hadid—to be "the most important person" in his personal journey.

"I love you more than words allow me to express, beyond proud to call you my daughter," Zayn, 31, wrote on Instagram in a birthday tribute to the toddler Sept. 19. "Grateful for every second I get to spend next to you, as you become the incredible person I know you already are."

Sharing a photo of himself holding Khai at the beach, the singer added, "Four years ago today my life changed forever and I wouldn’t be the man I am today without you."

And this year, Khai's birthday was truly out of this world. As seen in photos shared by Gigi, the young girl rang in her milestone with a massive cake shaped like Baby Yoda—a.k.a. Grogu—from the Star Wars franchise.

"Our girl is 4 today and we celebrated all week!!!" the supermodel wrote on Instagram Sept. 19. "She loves animals (fantastical ones too), music, baby yoda, all things nature & bugs, Descendants, anything squishy or miniature, and if possible- will be in the water from dawn til dusk."

 

Describing Khai as "curious, adventurous, loving, and oh so witty," Gigi continued, "It is my life’s greatest joy and pride to be your mama!!!! Thank you for the four best years of my life- you remind me to live life to the fullest every day, in the most simple & beautiful ways."

The 29-year-old added, "Your possibilities are endless, my sweetest love !!!!"

Gigi and Zayn were together on-and-off for five years before they welcomed Khai in 2020. Although the couple called it quits for the final time in 2021, they maintain a united front as co-parents with 50/50 custody of Khai.

"That she can be with both parents," Gigi—who is dating Bradley Cooper—told The Sunday Times last year, "makes me very happy."

Likewise, Zayn has described their co-parenting dynamic as "really good."

"I'm super full on, hands on with my child every chance I can be," he shared in a July 2023 episode of Call Her Daddy. "If I could get 60 percent, I would have it."

To see Khai's most adorable moments, keep reading.

For the latest breaking news updates, click here to download the E! News App