The actress stunned in a classic white saree with a golden border, paired with a sleeveless blouse.
She completed her look with red lipstick, golden jhumkas, a wristwatch, and a gajra in her hair.
Mouni also indulged in authentic delicacies as part of her celebration.
The actress was seen relishing a grand Onam sadhya, complete with festive flavours.
Sharing her photos on social media, she wrote: “Happy Onam to all celebrating.”
Several celebrities from Bollywood and South cinema also extended Onam wishes.
Her traditional ensemble paid homage to Kerala’s rich cultural heritage.
Netizens praised her as a “South Indian Sundari”, flooding social media with compliments.
On the work front, Mouni will star in David Dhawan’s film Hai Jawani Toh Ishq Hona Hai alongside a star-studded cast.