It brings to an end months of bitter feuding at the firm that runs CBS, MTV, Nickelodeon and Comedy Central.
It engulfed media veteran Sumner Redstone, his daughter Shari and Mr Redstone’s one-time protegé Dauman, who Ms Redstone had removed as head of National Amusements.
The new man at the top, at least temporarily, is Thomas Dooley. Currently chief operating officer, he is said to have the support of many Viacom staff.
But Shari Redstone is arguably the winner of the long-running dispute and will be backed by the new-look board.
Dauman will remain as non-executive chairman until September 13.
93 year-old Sumner Redstone still holds close to 80% of voting stock in Viacom and CBS through National Amusements, the cinema chain founded by his father.
The remaining 20% is held by Shari Redstone, who in recent years has had a difficult relationship with her father, and has previously refused an offer to sell her stake back to the company.