Singer Robin Thicke has become a father for the fourth time.

The Blurred Lines hitmaker's fiancee, model April Love Geary, debuted their baby son on Instagram on Friday night as she introduced fans to the latest addition to their family.

"My Luca Patrick, you are so perfect. Mommy & daddy love you so much," she captioned a sweet snap of herself cradling her newborn.

She did not announce any further details.

Little Luca is the couple's third child, following his big sisters Mia and Lola, who respectively turn three and two in February.

Thicke also shares 10-year-old son Julian with his ex-wife, actress Paula Patton.