The new ambassador made the comments at the US Embassy hours after presenting her credentials at Government House to Governor-General David Hurley on Monday, the final step in a long road to her appointment that included US Senate confirmation hearings.

Ms Kennedy, the daughter of US president John F. Kennedy and a major figure in Democratic party politics, said she felt a great deal of responsibility as Ngunnawal elders marked the beginning of her role with the first Welcome to Country and smoking ceremony to take place at the embassy.

It was also the first time the Aboriginal and Torres Strait Islander flags were displayed at the US Embassy.

Ms Kennedy began her role signalling there would be announcements in coming weeks about the significant AUKUS partnership, and saying she would try to advance the goals shared by Australia and the US.

"This is really one of the most important days of my life to become officially the United States ambassador to Australia, and to be here on this Ngunnawal land," she said.

"And to mark this moment with a ceremony that carries so much significance makes me feel a great deal of responsibility, and strengthens my commitment to work to strengthen the bonds between our nations and our people.

"The United States and Australia are the closest of allies, and we are global partners working for peace and stability, health, security and economic prosperity in this region and beyond."

Ngunnawal elder Dr Caroline Hughes delivered the Welcome to Country, and members of the Ngunnawal community presented Ms Kennedy with message sticks bearing a message of blessings.

In return, Ms Kennedy gave Ngunnawal elders a copy of her illustrated book, Poems to Learn by Heart. The exchange followed a meeting between Ms Kennedy and Ngunnawal elders at the embassy.

Dr Hughes later described the new ambassador as engaging and said she had asked informed questions that indicated her learning of Aboriginal people across Australia.

"For us as Ngunnawal people, she's going to be living on our land, so she was really open," Dr Hughes said.

Dr Hughes' mother, Aunty Loretta Halloran, had watched Ms Kennedy grow up as the daughter of a US president, and followed her life from afar via media reporting. She joined other Ngunnawal elders meeting the new ambassador, later describing her as "lovely".

Ms Kennedy responded to the Welcome to Country saying First Nations culture could inform how nations worked with each other.

"The traditions and values and culture that you have passed on and are passing on, have so much to teach the rest of us as we seek to reconcile our differences in this fractured world, and face the great challenge of caring for our environment."

Ms Kennedy assumes her post amid rising regional tensions, and as Australia and the US move to strengthen relationships with Pacific nations while China attempts to build influence and partnerships in the region.

The new ambassador and US Deputy Secretary of State Wendy Sherman are expected next month to visit Solomon Islands, where their fathers fought in World War II and where the US is competing for influence with China, which recently signed a security deal with the Pacific nation.

Ms Kennedy called AUKUS "a really significant partnership between three of the closest allies".

Asked about the planned visit to Solomon Islands, the AUKUS agreement and the Port of Darwin lease to Chinese company Landbridge, Ms Kennedy avoided controversy and indicated there would be more to announce on AUKUS in coming weeks.