A young mum who struggled to buy a coffee said she might now buy an entire cafe after winning $20 million on last night's Powerball draw.

The Sydney woman’s entry was one of the two division one winning entries.

As well as the $20 million, the Lewisham mum's PowerHit entry also won division two 19 times, netting her an extra $550,000.

“I’m in shock. I’m seriously still in shock. I’m just so happy. It’s huge," the woman said after being contacted about the win.

A Lewisham woman has won $20 million in a Powerball draw. (AAP) (AAP)

“I’m still pinching myself. I logged in to my account. I couldn’t believe if it was true or not so I said I’ll wait and see if I get a phone call.

“When I told my husband, I almost gave him a heart attack. I was calling him from the other room. I ran up to him and said ‘I think I’ve just won Powerball – it says it here’."

The woman said she had "been in shock" and hadn't slept since the win.

"I kept logging in and looking at it, thinking ‘Is it real? Is it not real?'"

The mum said her family's finances had been a "struggle" lately. (Powerball) (Supplied)

She said it had been a difficult time for her family recently as she and her husband had to juggle work and looking after their young children.

“It’s come at the best time. It’s been struggle after struggle,” she said.

“I can’t believe this happening. I’m still pinching myself."

Two days ago, she said, her husband had to scrape together all the change in his car to bring home a coffee for her.

The woman said they now planned to buy their own place. (Powerball) (Supplied)

“I couldn’t afford a daily coffee then, but I might go buy a café now," she said.

The winner said she was excited about the prospect of buying her first home for her young family.

“I’m definitely going to buy a house – we’re renting at the moment," she said.