Valued at pounds 100,000, it is described by the National Trust as 'an unusual and distinctive piece of great historical importance to Cliveden'.
The theft has occurred only months after Powis Castle in Wales lost five sculptures worth more than pounds 100,000. It is one of 21 thefts from National Trust properties this year.
Although the trust has stepped up security - last year spending pounds 2.2m on alarms for some statuary and increasing the number of guards among other measures - access to Cliveden at night would have been relatively easy.
Part of the house is a 31-bedroom hotel (leased out by the trust).
Joan of Arc was at least 100 yards away from the house in a secluded grove, making her an easy target. Thieves used a vehicle: they left behind tyre marks.
As the life-size statue (made by the amateur 19th century sculptor Princess Marie D'Orleans) weighs a quarter of a ton, police believe that at least two people would have carried out the job.
The theft took place between 12.40pm on Tuesday and 3.30pm yesterday. The National Trust was unable to explain why it took so long before anyone noticed.
Joan of Arc will be added to the National Trust's 1992 list of stolen items, of which eight are garden ornaments. There have been four attempted thefts.
It is symptomatic of the boom in architectural thefts: those from stately homes began only three years ago. There is evidence to suggest that statues are being stolen to order, perhaps for collectors on the continent.
A spokeswoman said: 'We have taken immediate steps to strengthen security at the grounds.
'This makes us even more determined to stop the erosion of the nation's heritage . . . We are prepared to divert more resources from repair to protection.'
David Horton of the trust's Thames and Chiltern region, said that the only other theft from his patch was earlier this year: two bronzes went missing from Hughenden Manor, High Wycombe, the former home of Disraeli.
That had a happy ending: the bronzes were recovered when the driver of the getaway van was stopped for speeding.