Google has said its British sales hit $5.64 billion in 2013, a rise of 16% on the previous year - its lowest growth rate in three years.
Britain is Google's biggest overseas market and the only one for which it breaks out separate sales figures.
In recent years the discrepancy between the company's high British revenues and low tax bill have prompted criticism from politicians.
Google declined immediate comment on the British sales figures.
Figures in Google's 10-K annual report showed British sales growth slowing from 20% in 2012 and 22% in 2011.
Google's growth in US sales also slowed in 2013, rising just 14%, compared to 34% in 2012.
The Mountain View, California-based company reported forecast-beating fourth quarter global revenue last month, despite a decline in prices for its online ads.
Google publishes its British tax bill in a separate British filing later in the year.
In 2012, the company had a tax bill of $55 million, including a £24 million charge in relation to previous years, on sales of $4.9 billion to British customers.