[6][7] Sigríður graduated from Reykjavik Junior College in 1991, studied law at the University of Iceland, and became an attorney in 2001.

[9] She played a pivotal role in the controversy surrounding the 'restored honour' of a convicted child sex offender which led to the dissolution of the Cabinet of Iceland under prime minister Bjarni Benediktsson in 2017.

[10][11] In 2017, she did not follow the recommendations of a special committee list of the most qualified judges for the newly formed Icelandic court of appeals and instead hand-picked 4 of them, including the wife of fellow Independence Party parliamentarian Brynjar Níelsson.

[12] On 12 March 2019, the European Court of Human Rights ruled that the appointments had been made illegally.

[13] On 13 March 2019, in the aftermath of the ruling, Sigríður announced that she would resign as Justice Minister.