The 26-year-old is currently suspended by the English Cricket Board (ECB) as he waits to find out whether he will be prosecuted for an incident in September which saw him attack two men outside of a nightclub.
The ECB's stance means that he has been unable to participate in The Ashes in Australia so far, although hopes were raised earlier this week when he was spotted boarding a flight to New Zealand.
Stokes subsequently began talks with Canterbury and has now concluded terms on a loose arrangement that will see him play domestic cricket in his homeland, while remaining geographically nearby should his situation with England change.
"After the approach from Ben's representatives everything has happened very quickly for us to the extent that we are now delighted to welcome Ben into the team," said Gary Stead, Canterbury's director of cricket.
"Ben will bring international experience to what is a relatively youthful changing room. He will also bring depth to our seam attack which has been affected by a string of injuries and provide more balance and firepower to our batting line up.
"While Ben awaits the outcome of an investigation underway in the UK, he wants to maintain his fitness and his connection with the game. He is a brilliant all-round player and we are really pleased to have secured one of the world's best players in our domestic competition.
"The team have expressed their excitement about the opportunity to learn from and play with Ben."
Stokes could make his debut for Canterbury this Sunday in a 50-overs game.