Today show co-host Karl Stefanovic has reportedly separated from his wife after 21 years of marriage.

The 42-year-old moved out of the family home he shares with his wife, Cassandra Thorburn, 44, and three children in recent weeks, according to News Limited.

He is staying at his friend James Packer's Bondi apartment, the report stated.

Friends of the couple were quoted as saying they were 'stunned by the separation'.