The lucky man, known only as Mr M, scooped the seven-figure sum without even touching a ticket.
He played EuroMillions through national-lottery.co.uk and earned his life-changing prize in the EuroMillions UK Millionaire Maker draw on July 3.
Interactive winners have the opportunity to release their name, remain anonymous or, like Mr M, release some details through partial publicity.
Andy Carter, the senior winners’ advisor at the National Lottery, said: “Huge congratulations to Mr M for winning this fantastic prize without even touching a ticket – after a few simple clicks he has become a millionaire!
“With many people leading busy lives, playing online is becoming increasingly popular.
“It means you can make sure your lucky numbers are always in the draw and your ticket is always checked.”