The First Minister reacted to news the Brexit Party would not contest any of the seats won by the Tories in 2017 by claiming Boris Johnson "is having his strings pulled by Nigel Farage".
Mr Farage told supporters in Hartlepool the Prime Minister had signalled a "big shift of position" on Brexit, including an apparent promise to not extend the transition period beyond 2020, something he said was a "huge change" from the Conservatives' previous position.
Ms Sturgeon said: "The Brexit Party's announcement today really does underline the fact that Boris Johnson and Nigel Farage are joined at the hip and, frankly, any form of Brexit that is acceptable to Nigel Farage is going to be deeply damaging for Scotland.
"I suspect there are many traditional Tory Party voters here in Scotland and elsewhere across the UK who will be appalled to learn that their party has effectively become the Brexit Party.
"If you vote Tory, you get the Brexit Party and its view of the world, and I don't think that's what the vast majority of the people in Scotland want.
"We see a Tory Party becoming ever more extreme and right-wing, and out of touch with the majority of people in Scotland.
"It really does underline the view that if you don't take Scotland's future into Scotland's hands at this election, then the danger is our future is imposed upon us by Boris Johnson and Nigel Farage."
Welcoming the news, Ms Sturgeon said: "The Greens make their own decisions and it's never an easy decision for any party to take, to stand down, and I certainly am grateful that the Greens are thinking carefully about these things.
"Westminster elections are fought on first past the post and if we don't unite to defeat the Tories - and the SNP is the main challenger in every Tory seat in Scotland - then the danger is that they get in by the back door.
"The message to people across Scotland has to be: If you don't want a Boris Johnson Tory government with their strings being pulled by Nigel Farage dictating our future, then voting SNP to get rid of the Tories, escape the Brexit mess and put our future into our own hands is the only way forward at this election."