The Scottish National Party leader made the shock announcement today at Bute House in Edinburgh.
She confirmed her plan to remain in office until a successor is elected and shared that she intends to remain active in politics after stepping down.
She said she knows the 'time is now' for her to resign and said: "But for those who do feel shocked, disappointed, perhaps even a bit angry with me, please be in no doubt this is really hard for me.
"My decision comes from a place of duty and of love. Tough love perhaps but love nevertheless for my party and, above all, for the country."
Sturgeon, 52, served as First Minister since November 2014, when she took over from Alex Salmond after the independence referendum.
She has since become the country’s longest-serving First Minister. Sturgeon has been a member of the Scottish Parliament since 1999 and became the deputy leader of the SNP in 2004.
While in power, Sturgeon introduced a freeze on rents for public and private housing to help with the cost of living crisis in September after calling it a 'humanitarian emergency'.
She also announced that train fares on ScotRail, which came into public ownership in 2022, would be frozen until March 2023 at the earliest.
Scotland also became the first country in the world to provide free period products in 2022.
The Period Products Act (Free Provision) came into effect in August, enabling local authorities and education providers to distribute products to anyone that needs them free of charge.
The incredible change came about after it was reported that one in 10 schoolgirls has experienced period poverty across the UK, according to Plan International UK research.
More recently, she has become embroiled in the arguments regarding transgender prisoners as a result of the Isla Bryson case.
Bryson is a Scottish transgender woman who was convicted in January for the rapes of two women that she committed before her transition.
At a news conference and in the Scottish Parliament earlier this month, Sturgeon was asked repeatedly whether she thought Bryson was a man or a woman to which she called her 'the individual' rather than using gendered language or pronouns.
But she eventually said: "My comments about her, err, the person, being a rapist is in context of what should happen to them within the prison service."
The first minister then later added: "She regards herself as a woman. I regard the individual as a rapist."
Sturgeon also tried to defend the Gender Recognition Reform (Scotland) Bill passed by MSPs in December 2022.
The bill would reduce the age limit to formally change one's gender to 16 and remove the requirement for a medical diagnosis.
After the Supreme Court ruled in November that she cannot hold another referendum without approval from UK ministers, Sturgeon vowed to make the next general election a ‘de facto referendum’.
However, the results from a survey released on Monday (13 February) indicated that two thirds of Scots rejected the idea.
During her speech today in Edinburgh, Sturgeon said: "Winning independence is the cause I have dedicated a lifetime too. It is a cause I believe in with every fibre of my being and it is a cause I’m convinced is being won.”
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