The title for the shortest-serving PM was earlier held by George Canning, who passed away in 1827 after 119 days in the office. Alec Douglas-Home comes in third place, who lost the 1964 election after being prime minister for one year and one day.
Truss announced her resignation outside 10 Downing Street on Thursday, following challenges to her political authority after her government announced a drastic, unsupported policy decision to slash taxes, which reportedly lost the country over £60 billion.
Her statement came close on the heels of her meeting with the chair of the 1922 Committee, Graham Brady, deputy PM Thérèse Coffey, and Conservative Party chair, Jake Berry.
Truss' Resignation Speech
Announcing her resignation, Truss said, "I recognise that, given the situation, I cannot deliver the mandate on which I was elected by the Conservative party. I have therefore spoken to His Majesty the King to notify him that I am resigning as leader of the Conservative party."
She also said that after her meeting with Brady, an agreement was reached to conduct a leadership contest for the next Conservative Party leader within a week.
"This will ensure that we remain on behalf to deliver our fiscal plans and maintain our country’s economic stability and national security. I will remain as prime minister until a successor has been chosen," she said.
Just a day ago, Truss had rejected calls for her resignation in Parliament, saying, "I am not a quitter".
Approval ratings for her and the Tories had been plummeting over the last few weeks, with pollsters calling her the "worst-performing PM" they had ever tracked.
On 14 October, Truss had fired her then chancellor of the exchequer Kwasi Kwarteng, who also became the second shortest-serving finance minister in the country's history - serving for only 38 days - behind Iain Macleod, who passed away after serving for 30 days.
He had been replaced by Jeremy Hunt, who all but tore up most of Truss' economic plans.
The PM had also lost her home secretary, Indian-origin Suella Braverman, who resigned from her post on Wednesday, 19 October, having written a scathing letter to the PM.
Meanwhile, the Opposition Labour Party has reiterated its demand for an immediate general election. Labour leader Keir Starmer said that after 12 years of "Tory failure, the British people deserve so much better than this revolving door of chaos."
"The Tories have set record-high taxation, trashed our institutions and created a cost-of-living crisis. Now, they have crashed the economy so badly that people are facing £500 a month extra on their mortgages. The damage they have done will take years to fix.”'Keir Starmer
Lettuce vs Truss: Lettuce Wins
Twitter was abuzz with jokes and memes about Truss, who was even compared with a lettuce by The Economist, a prominent news journal, as well as an entertainment tabloid called The Daily Star.
The Daily Star even livestreamed a store-bought lettuce, with a shelf-life of around 10 days, next to a photo of Truss, and asked, "Day one: Which wet lettuce will last longer?"
The livestream had attracted hundreds of thousands of views after it was posted on 13 October. For effect, the vegetable was even donned with googly eyes, and sometimes even a wig and an eye mask.
As it turns out, the lettuce has lasted longer than Truss did.