It beat the previous best of £8.6m set by the first Potter film a year ago, the film's producers Warner Bros said.
During its first three days, The Chamber of Secrets raked in about $142m (£89m) at cinemas around the world, smashing a number of records.
In North America it became the third highest-earning opening film in history with receipts of $87.6m (£55m), slightly down on the $90.3m (£56m) taken by its predecessor The Sorcerer's Stone.
The film took $54m ( £34m) in seven other key worldwide markets.
The Chamber of Secrets opened on Friday at 3,682 cinemas in the US, making it the biggest opening of any film in North American history.
It also dominated another 3,284 screens across the world, in the UK, Malaysia, Singapore, Germany, Austria, Taiwan and the Philippines.
In Germany, 2.3 million fans flocked to see the film, which took $15.6m (£9m).
Queues
In Taiwan it took about $3.14m (£1.89m), setting a new industry record in the capital Taipei with $1.15m (£0.72m) income.
In the US, a number of Harry lookalikes took time off school and donned capes and round glasses as long queues continued throughout the weekend.
But its US performance failed to threaten the all-time record set by Spider-Man which took $114m (£71m) in its first three days in May.
However, Warner executives said they were delighted with Potter's performance, despite jitters about how it would compare with the first film.
"We are thrilled with how well the picture has done," said one senior studio official. "It soared to new heights in the UK... and set multiple industry records in Europe and Asia."
As the film was making its big-screen debut in Malaysia, pirated DVD versions of the film were on the streets of the capital Kuala Lumpur for just $3.
Malaysia is regarded by the entertainment industry as one of Asia's piracy hotspots alongside Taiwan, the Philippines and Singapore.