The pact with Virgin will bring to 80 percent Yahoo's coverage of the British population using mobile search, Yahoo said, referring to data from m:metrics.
Virgin has four million mobile subscribers in the UK.
Yahoo has 70 such agreements with other telcos worldwide, providing the internet company a potential reach of about 850 million mobile phone users.
After UK, Yahoo now sets its sights on France, Germany, Italy and Spain for similar partnerships.
By signing deals with telcos, Yahoo appears to be hoping to grab a lead over rival Google in the growing mobile search and ad markets. Google leads desktop-based internet search worldwide.