The First Minister confirmed she will attempt to secure the approval of MSPs at Holyrood next week to start negotiations with the UK Government on a deal that would allow a legally binding ballot to be held.
That could see a second independence vote take place as early as autumn 2018 - just four years on from when Scots voted by 55% to 45% to stay part of the United Kingdom.
Prime Minister Theresa May said Ms Sturgeon’s decision was “deeply regrettable” and warned the move was setting Scotland on a course for “more uncertainty and division”.
The move comes after nearly two thirds (62 per cent) of Scots opted to stay in the European Union in June 2016, but the UK as a whole voted for Brexit.
Prime Minister Theresa May has so far avoided saying whether or not she would grant permission.
Responding to Ms Sturgeon’s announcement, Mrs May said a second independence referendum would set Scotland on course for “uncertainty and division” and insisted that the majority of people in Scotland did not want another vote on the issue.
She added: “The tunnel vision that SNP has shown today is deeply regrettable.
“Instead of playing politics with the future of our country, the Scottish government should focus on delivering good government and public services for the people of Scotland. Politics is not a game.”
But speaking at her official Bute House residence in Edinburgh, Ms Sturgeon said the people of Scotland must be offered a choice between a “hard Brexit” and becoming an independent country.
The Scottish government has published proposals which it says would allow Scotland to remain a member of the European single market even if the rest of the UK leaves, which Mrs May has said it will.