The SNP leader made the bold prediction despite the country overwhelmingly voting to stay in the UK less than three years ago.
Speaking ahead of Thursday's general election, she again laid out her demands for a second vote on breaking up the union.
Asked if she would get her wish before 2025, she told ITV: "I think Scotland will be independent, yes. But that's a choice for the Scottish people."
I believe Scotland will be independent, I've always believed that
She refused to be drawn on an "arbitrary date" but added: "I believe Scotland will be independent, I've always believed that.
"Actually, Scotland becoming independent – we won't leave the British Isles.
"Scotland will just move from becoming a devolved country to an independent country.
"But those links and relationships that hold the British Isles as an entity will continue."
Nicola Sturgeon claimed Scotland will become independent by 2025 Nicola Sturgeon's comical moments on the campaign trail Mon, May 22, 2017 PA 1 of 13
SNP leader Nicola Sturgeon stops for an ice cream after making an election campaign visit to Scottish Gas HQ in Granton, Edinburgh
The First Minister, who wants Scotland to stay in the EU, also demanded a key role in Brexit talks when they begin later this month.
She said it would be "democratically unsustainable" if Scotland's voice is not heard during negotiations with Brussels.
Get Quotes on Home Insurance
Mrs Sturgeon added: "What we're now being told is, 'Shut up, Scotland, because nobody in the rest of the UK is interested in what you want to say'."
She insisted the country would remain 'close' to rest of the UK
And she insisted her timetable for a fresh independence vote is "as it's always been" – between autumn 2018 and spring 2019.
She said: "I set out those dates because that is what Theresa May is telling us right now the end of the process will be.
"She has said that the terms of the Brexit deal, the new relationship with Europe, will be known before the UK exits the EU in the spring of 2019."
Theresa May is refusing to grant Sturgeon another referendum
Mrs May has repeatedly refused Mrs Sturgeon's demands for a second poll on breaking up the UK, saying she is focused on Brexit.
Speaking during a trip to Edinburgh in March, the PM said: "My message is very clear – now is not the time. I've explained the reasons why.
"I think we should be working to get the right deal for Scotland and the UK with our future partnership with the European Union."