Daniel Tostevin, a Year 4 teacher, came top of the class when BOTB handed him the keys to a Mercedes A45 AMG.
The 24-year-old was lost for words when he was surprised by Christian Williams from BOTB on his way out to work.
Daniel, of Fareham Quays, said: ‘I’m over the moon, I honestly can’t believe my luck.
‘I’ve been playing the competition for years but I never dreamed I’d actually ever win my dream car.’
Christian delivered the good news to Daniel last week in the prize-giving.
‘I initially thought it was the postman delivering something when the doorbell went, but as soon as I saw Christian in his BOTB gilet through the peephole I was pinching myself,’ Daniel said.
‘I waited until the end of the day to tell the children in my class the amazing news, I didn’t want to get them over excited all day.’
BOTB was founded by William Hindmarch in 1999 and has handed over the keys to more than £22m worth of supercars.
Christian said Daniel, a teacher at Thornhill Primary School in Southampton, was a worthy winner.
‘I have one of the best jobs in the world, handing people the keys to their dream car,’ said Christian.
‘And to be able to give an A* result to a teacher is the greatest feeling.’
BOTB first opened at Heathrow Airport in 1999, with Daveeda Shaheen scooping the first prize.
The firm, based in Fulham, clocked up its 350th winner in 2016 and uses former professional footballers to independently judge each competitions.
Former England international Sol Campbell, the man who skippered Pompey to FA Cup final glory ten years ago, has taken part.