Camelot said this evening that the UK ticket-holder had scooped the EuroMillions prize.
The numbers were 14, 15, 22, 35 and 48, while 03 and 08 were the lucky star numbers.
The company added that three UK winners who matched five numbers and a lucky star were in line for nearly £100,000.
Each can claim £93,099.60, while the overall winner gets £171,815,297.80.
Camelot’s Andy Carter, senior winners’ adviser at The National Lottery, said: ‘What an amazing night for one UK ticket-holder who has scooped the giant £171 million EuroMillions jackpot.
‘This winner has just become the third biggest National Lottery winner of all time and the sixth UK EuroMillions jackpot winner this year alone.
‘Players are urged to check their tickets and to give us a call if they think they are tonight’s lucky winner.’
Though tonight’s overall prize is huge, it did not break the record £195 million jackpot won by another UK ticket holder earlier this year. It was claimed a day later but the winner chose to be anonymous.
The identity of tonight’s winner was not immediately clear.
But Gloucestershire couple Joe and Jess Thwaite publicly celebrated their £184 million prize after a May 10 win.