Narendra Gill, 52, stole the £130,000 winning ticket from retired deliveryman Frank Gowland, 81, after checking it for him at her shop in Leeds. Mr Gowland was unaware that his ticket had five winning numbers and one Lucky Star until weeks later the police notified him it had been stolen.
The shopkeeper was caught out by Camelot, who run the lottery.
Staff at the operator of the UK National Lottery became suspicious after hearing her try to check the ticket on the phone while serving customers at her GT News shop in West Yorkshire.
She admitted to working at the now-closed shop in White Rose Shopping Centre but claimed she was gifted the ticket and had no idea where it was bought.
The police were notified by the lottery company and they checked the CCTV footage which showed Mr Gowland get into a car at the shopping centre with his wife Sue, 77.
Mr Gowland explained that the turn of events came as “quite a shock”.
He told The Sun: “The whole thing has been quite a shock.
“I had no clue I’d won until I got this phone call.
“I couldn’t hear what the PC was saying so I asked my stepson to deal with it.
“He said to the officer, “You must be joking, this is a scam”. Anyway, it wasn’t and I had won.”
READ MORE: Puppy who smiles at every visitor finds forever home
“They told me the woman phoned Camelot, 15 minutes after I left, claiming to have a winning ticket.
“But they smelt a rat. She was lying through her teeth. It’s unbelievable really. I might never have known.”
The father-of-two eventually received his payout in November last year and said the money has helped make life “a bit more comfortable”.
He has bought a new car, given money to family, and purchased a walk-in shower for his wife, who has health problems.
Shop manager Gill, from York, admitted theft and fraud and was jailed on Thursday at Leeds crown court for 28 months.
Recorder Dafydd Enoch QC told her she had been “unbelievably cruel”.
He added: “People who work in these places need to hear the message that you cannot abuse your position when it comes to dealing with millions of pounds. Trust is so important.”