The event will be attended by close friends and family only but a bigger, more glamorous second ceremony will be held later on in romantic Venice, the Daily Star reported.
In August, a human rights lawyer visited Kensington and Chelsea register office to get the wedding licence.
The couple later disclosed they would first tie the knot at a formal civil ceremony at Chelsea Old Town Hall.
The Venice bash would likely be on September 27, with an expected 60 guests including Clooney's movie pals such as Matt Damon.
The 53-year-old actor started dating his London-based barrister fiancee last September.
They got engaged in April.
Image: Amal Alamuddin and George Clooney. Photograph: Andrew Goodman/Getty Images for Celebrity Fight Night
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