The Scottish first minister claimed independence was Scotland’s “route to avoiding the worst of the damage Brexit will do” and said another vote should be held “in the lifetime” of the current Scottish parliament, which is due to end in 2021.
The last referendum took place in 2014 and delivered a vote against independence.
The SNP leader said she would bring forward legislation this year to pave the way for another referendum.
Outlining her plan in a speech to the Scottish parliament, Ms Sturgeon said: “My party was elected with a mandate to offer that choice within this parliamentary term should Scotland be taken out of the EU against our will. There is also a majority in this chamber for that position and polling evidence suggests a majority in Scotland want a choice on independence, though opinions vary on timing.
“There are some who would like to see a very early referendum; others want that choice to be much later.”
Rejecting calls for a referendum this year, she continued: “To rush into an immediate decision before a Brexit path has been determined would not allow for an informed choice to be made. However, if we are to safeguard Scotland’s interests, we cannot wait indefinitely.
“That is why I consider that a choice between Brexit and a future for Scotland as an independent European nation should be offered in the lifetime of this parliament.
“If Scotland is taken out of the EU, the option of a referendum on independence within that timescale must be open to us. That would be our route to avoiding the worst of the damage Brexit will do.”
Ms Sturgeon said the UK’s decision to leave the EU had changed the circumstances since the last Scottish independence referendum.
She said: “The case for independence is even stronger now given the profound changes that have taken place in the UK since 2014.
“In that time we have seen the limits of Scotland’s influence within the UK and, in sharp contrast to that, the power that independent nations have as members of the EU.
“Independence would allow us to protect our place in EU, it would enable us to nurture our most important relationships – those with the other countries of the British Isles – on the basis of equality, and it would mean that decisions against our will and contrary to our interests cannot be imposed on us by Westminster.”
Any plan for a second vote would need to be approved by the government in London.
Theresa May has said she will not agree to another independence poll, but Ms Sturgeon said she was confident that position “will prove to be unsustainable”. The first minister said she was acting now so “we won’t squander valuable time ... in a standoff with a UK government that may soon be out of office”.
She added: “Those who oppose independence are of course entitled to argue that case, but it must be for the people to decide.
“If we are successful in further growing the support and the demand for independence, then no UK government will be able to deny the will of the people or stop that will being expressed.”