The company, whose gaming arm comprises sports book www.williamhill.co.uk and web casino www.williamhillcasino.
co.uk, posted the figure in its results for the half-year to 2 July.
It reported a strong rise on the £2.5m posted for the six months to 26 June in 2001.
Turnover grew 77.5 per cent, from £111.3m to £197.6m, over the same period.
William Hill said that an increase in activity around the World Cup resulted in a significant leap in online marketing and numbers of new customers.
Williamhill.co.uk set up 64,000 new accounts during the period, to give it a total of 126,000 active customer accounts on 2 July. The casino operation reported 44,000 active customers.