The opposition conservative Liberal Party leader Peter Dutton, who had been labelled "DOGEy Dutton" by Labor after echoing Trump policies to cut thousands of public service jobs including diversity and inclusion roles, lost his seat.
Ley said her appointment as the first female leader of the Liberal Party "sent a signal" to Australian women, although her agenda would be "much more than that", flagging the need for new policies on economic and tax reform.
"We did let women down, there is no doubt about that, and it is true that the number of women supporting us is declining and I want to rule a line under that," she told a press conference in Canberra, reflecting on the conservative party's loss.
The Liberal Party has lost city seats in Sydney and Melbourne to women who ran as independent candidates with policies supporting climate change and gender equality in the last two elections.
Ley said the Liberal Party needs to "meet modern Australia where they are".
"Government is always formed in the sensible centre," she added.
A former pilot who mustered livestock in Australia's vast outback and raised three children on a farm before graduating from university, Ley entered parliament in 2001.