The Hollywood star married Amal Alamuddin last Saturday, and he treated his new bride to the home an hour away from London, which is where they are reportedly considering raising a family.
A source told The Sun on Sunday newspaper: "George has all the money in the world but wanted to give Amal something special to mark their marriage.
"Buying her a house must be up there with the most expensive wedding gifts in history, but the thought behind it was to give them a proper place to call home in the future.
"George will still travel the world for his movies, but they intend for this to be their British base. They want it to be the place where they bring up a family. They have already talked about having kids."
The home will allow human rights lawyer Amal to continue her work in London, and the newlyweds hope to spend most of their time there.
As well as a panic room, the mansion also features living quarters for 'The Monuments Men' star's security team.