The actor who played Mr. Big on the Sex and the City series has announced he is expecting his second child with his wife Tara Lynn Wilson.

Chris Noth, who will be 64-years-old when his second child is born, revealed the news on Instagram by posting a photo of his wife.

"Orion is getting a brother - I better get my ass into shape," he joked.

Sex and The City co-stars congratulated Noth in the comments, including Sarah Jessica Parker who played Carrie Bradshaw.

View this post on Instagram

Orion is getting a brother- I better get my ass in shape.

A post shared by Chris Noth (@chrisnothofficial) on

"Oh. My. G-d!!!!!!!!!! I'm so happy for you both!!! Xx," the star wrote.

The on-and-off-again relationship between Carrie Bradshaw and Mr. Big hooked viewers for the show's six seasons.

Chris Noth in the movie Sex and the City 2. Photo / Supplied
Chris Noth in the movie Sex and the City 2. Photo / Supplied

Kristin Davis, who played Charlotte York Goldenblatt on the show also offered her congratulations, commenting "Yay yay yay!".

Noth and Wilson married in 2012, after meeting at a NYC music venue he co-owns in 2002.

They have an 11-year-old son together named Orion.

Noth is also known for his roles as Law and Order detective Mike Logan, and Peter Florrick on the show The Good Wife.