The' Sex in the City' star made the announcement only 24 hours after she wrote a moving plea on social media for help to track down her missing brother.
The 61-year-old actress had taken to Instagram on Sunday morning to post that Chris had been missing since last Tuesday from his home in Alberta, Canada,
"MISSING! This is my brother Christopher Cattrall or Chris as we call him," Kim Cattrall said on Instagram sharing the above pic of them together.
"He has been missing since Tuesday, January the 30th from his home in Lacombe, Alberta Canada. His keys, cell phone,& wallet left on the table and his front door unlocked. This is not like Chris. He he would never leave his unlocked home without those items nor his 7 beloved dogs."
But just 24 hours later she had another announcement to make. "It is with great sadness that myself and my family announce the unexpected passing of our son and brother, Chris Cattrall," she wrote on Instagram.
The cause of death has not been made public at this time.

It is with great sadness that myself and my family announce the unexpected passing of our son and brother, Chris Cattrall. At this time we ask for privacy but we want to thank you all on social media for your outpouring of love and support in this trying time.

A post shared by Kim Cattrall (@kimcattrall) on Feb 4, 2018 at 1:00pm PST