The Hollywood star and activist accrued more than 1.8 million followers within two hours of joining the social media platform on Friday.
Posting a photo of a letter sent to her by a teenage girl in Afghanistan, the Eternals star said she feared the Afghan people were “losing their ability to communicate on social media and to express themselves freely” following the Taliban takeover of the country.
Jolie, a special envoy for the United Nations High Commissioner for Refugees, said she had come to Instagram “to share their stories and the voices of those across the globe who are fighting for their basic human rights”.
Her short biography on the site noted that as well as working with the UN she is also a mother and filmmaker.
“I was on the border of Afghanistan two weeks before 9/11, where I met Afghan refugees who had fled the Taliban. This was 20 years ago,” she wrote.
“It is sickening to watch Afghans being displaced yet again out of the fear and uncertainty that has gripped their country.
“To spend so much time and money, to have blood shed and lives lost only to come to this, is a failure almost impossible to understand.
“Watching for decades how Afghan refugees – some of the most capable people in the world – are treated like a burden is also sickening.
“Knowing that if they had the tools and respect, how much they would do for themselves. And meeting so many women and girls who not only wanted an education, but fought for it.
“Like others who are committed, I will not turn away. I will continue to look for ways to help. And I hope you’ll join me.”
The letter, which had been anonymised by Jolie, detailed the fears of a young woman living in Afghanistan, who said it had become more difficult to attend school because of Taliban patrols.
The girl also said she worried things would go back “20 years” to when women had “no rights”.