Robin Thicke and April Love Geary Celebrate Son Luca's Birthday: 'Every Day with You Is Sunshine'

April Geary/instagram

Robin Thicke and wife April Love Geary are celebrating their little boy.

On Sunday, Geary, 28, shared a photo from son Luca Patrick's second birthday which included a red-and-black racecar-themed celebration.

"Happy birthday to the best boy in the whole world!!!!" the model mom captioned the family photo, where she holds Luca as Thicke leans in. "The easiest, happiest, cutest boy. Love you Luca boy! ♥️"

On Monday, the "Lost Without You" singer, 45 — who is also dad to daughters Lola, 3, and Mia, 4, whom he shares with Geary, and son Julian, 12, with ex-wife Paula Patton — shared a birthday tribute to his youngest on Instagram.

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"Happy 2nd birthday to the sweetest, cutest boy in the whole wide world! Every day with you is sunshine," the proud dad wrote alongside adorable images of the toddler. "When you giggle, it makes everything in life make sense. I love you Luca Patrick Thicke!!!"

He then added, "Thank you @aprillovegeary I love you! ❤️"

The "When You Love Somebody" singer opened up to PEOPLE last year about how being a dad "has fed my soul" — particularly since the 2016 death of his own dad, Growing Pains star Alan Thicke.

Fatherhood "brought me back," he said. "I think probably when I lost my father, it's no coincidence that I've had three children in the last few years … because that's how big that hole is."

"I remember a friend of his and mine said, 'A big tree has fallen.' That's what my dad was. He was the big tree," he continued.

"Now here I am, this medium-size tree, and I've got to grow my branches and I've got to secure my roots and I've got to protect everybody that he was protecting also," added Thicke. "For me, it's a job that I'm very happy to do, and every day I try to make him proud of me."