Stokes was omitted from the England touring party to Australia and remains suspended pending the outcome of a police investigation into an incident outside a Bristol nightclub in September.
However, Canterbury Cricket Association (CCA) Director of Cricket Gary Stead confirmed the 26-year-old had signed as an overseas player and would be available for a one-day match against Otago on Sunday in Rangiora, near Christchurch.
"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," Stead said in a statement on Thursday.
"While Ben awaits the outcome of an investigation underway in the UK, he wants to maintain his fitness and his connection with the game."
The confirmation came a day after police said they had passed a case file to Britain's Crown Prosecution Service and were seeking advice over whether to bring charges against Stokes following his arrest on suspicion of causing actual bodily harm.
The police said that a 27-year-old man had "suffered a fractured eye socket" in the incident involving Stokes.
The CCA said Stokes's signing had been agreed by the England and Wales Cricket Board (ECB) and sanctioned by New Zealand Cricket.
New Zealand-born Stokes arrived at Christchurch airport on Wednesday and said he was back to catch up with family but declined to comment on his cricket plans.
The ECB distanced itself from Stokes's visit Down Under, describing it as a "private" trip in a statement on Tuesday.
That did little to alleviate suspicions in neighbouring Australia of a plot to parachute Stokes back into the England team midway through the Ashes.
Pundits in Australia have accused the ECB of a cover-up and a media throng greeted Stokes at the airport along with his parents.
The Stokes sideshow has overshadowed England's Ashes tour and they lost the first test in Brisbane by 10 wickets without their star all-rounder. The second starts in Adelaide on Saturday.
New Zealand coach Mike Hesson welcomed the prospect of Stokes playing as a boon for the domestic cricket scene.
However, former test cricketer and Canterbury stalwart Peter Fulton said he was uncomfortable with it, comparing Stokes's situation with Ken McClure, a local player who voluntarily stood down last week after pleading guilty to an assault charge during a pre-season trip.
"While it would be easy to draw direct comparisons between the position taken recently with another player, we have to reiterate that in that situation the player was free to play until such time as he pleaded guilty to the charges," Canterbury CEO Jez Curwin said.
"We are very comfortable that he wants to come to play for Canterbury for all the right reasons and get back on the park.
"The Ashes series is an obvious connection however that has not been a consideration for us or Ben at this time, he is just keen to be able to work again."
(Reporting by Ian Ransom in Melbourne; Editing by Greg Stutchbury)
