Naomi Watts celebrates her son Kai's 12th birthday with a sweet tribute saying how 'lucky' she feels being his mother

She shares two beautiful children with her ex-partner Liev Schreiber.

And on Sunday, Naomi Watts paid tribute to her youngest son, Samuel 'Kai' Schreiber, on his 12th birthday.

Taking to Instagram, the 52-year-old actress revealed how 'lucky' she felt being Kai's mother and shared several pictures of her little boy.

Proud mother! On Sunday, Naomi paid tribute to Kai on his 12 birthday. Taking to Instagram, she revealed how 'lucky' she felt being Kai's mother

Proud mother! On Sunday, actress Naomi Watts paid tribute to her youngest son, Samuel 'Kai' Schreiber, on his 12th birthday. Taking to Instagram, the 52-year-old actress revealed how 'lucky' she felt being Kai's mother and shared several pictures of her little boy

'Happy birthday to Kai! Your beautiful spirit, wicked humor and quick mind inspire us all,' she captioned her post.

'I feel so lucky to be your mummy. Every day you blow me away. The depth of your thinking is truly special. You are my angel.'

In the accompanying pictures, Kai is shown biting into a red capsicum while at the beach, and posing for the camera in a series of artistic shots.

He is also shown enjoying quality time with his famous parents and brother, Sasha.

'Happy Birthday to Kai!' In the accompanying pictures, Kai is shown biting into a red capsicum while at the beach, and posing for the camera in a series of artistic shots

'Happy Birthday to Kai!' In the accompanying pictures, Kai is shown biting into a red capsicum while at the beach, and posing for the camera in a series of artistic shots

Well-wishes: Several of Naomi's famous friends, including Kate Hudson and Julianne Moore, also wished Kai a happy birthday in the comments section

Well-wishes: Several of Naomi's famous friends, including Kate Hudson and Julianne Moore, also wished Kai a happy birthday in the comments section 

Several of Naomi's famous friends, including Kate Hudson and Julianne Moore, also wished Kai a happy birthday in the comments section.

Meanwhile, Liev celebrated Kai's birthday with a sweet Instagram post of his own. 

'Happy Birthday, Kai! I love you beyond beyond,' wrote the American actor, 53. 

Family life: Naomi and her ex-partner Liev Schreiber share two sons: Samuel, known as Kai, and Alexander, known as Sasha. Pictured: Naomi with her sons on May 16, 2016, in New York

Family life: Naomi and her ex-partner Liev Schreiber share two sons: Samuel, known as Kai, and Alexander, known as Sasha. Pictured: Naomi with her sons on May 16, 2016, in New York

Liev is in Italy shooting the movie Across the River and Into the Trees, an adaptation of the Ernest Hemingway novel of the same name.

He and Naomi also have another son, Alexander 'Sasha' Pete, who is 13.

The couple, who split in 2016 after 11 years together, amicably co-parent their boys. 

Wishing him well from afar: Liev is in Italy shooting the movie Across the River and Into the Trees, an adaptation of the Ernest Hemingway novel of the same name. He celebrated Kai's birthday with a sweet Instagram post of his own on Sunday

Wishing him well from afar: Liev is in Italy shooting the movie Across the River and Into the Trees, an adaptation of the Ernest Hemingway novel of the same name. He celebrated Kai's birthday with a sweet Instagram post of his own on Sunday

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