Her appointment alongside incumbent Justice Susan Crennan marked the first time two women sat concurrently on the High Court bench.

[12] On 29 November 2016, Prime Minister Malcolm Turnbull and Attorney-General George Brandis announced Kiefel's appointment as Chief Justice of Australia.

[13] Giving the inaugural Lord Atkin Lecture in November 2017, Kiefel expressed her disapproval of the prevalence of judicial dissent, which she believes should be reserved for only the most important cases.

She said law students should devote more attention to "mundane majority opinion", and described judges who frequently dissent as "somewhat self-indulgent".

She further observed that "humorous dissent may provide the author with fleeting popularity, but it may harm the image the public has of the court and its judges".

[17] Kiefel was on the panel that handed down a unanimous verdict during the 2017–18 Australian parliamentary eligibility crisis, in which several high-profile politicians lost their jobs owing to having dual citizenship, whether unknowingly or knowingly.

[18] In June 2020, Kiefel announced that the High Court had in 2019 commissioned an independent investigation into sexual misconduct allegations against her former colleague Dyson Heydon.

[19] She was one of three dissenters who held the minority view in a 4-3 split[20] in Love v Commonwealth (2020), which found that Aboriginal Australians are not subject to the aliens power in section 51(xix) of the constitution.

[21] In general her judgments have been regarded as conservative, but ANU professor Heather Roberts commented that she was hard to label, and that she "values the court as an institution".

Justice Kiefel was chosen to recognise her distinguished contributions to the legal profession and for leading the way for women in the industry.