Catherine Connolly has said she will make sure all voices are nurtured and heard during her presidency.
Speaking at Dublin Castle where she was inaugurated as the 10th president of the Republic of Ireland she said the country has been undergoing seismic changes since the end of the Cold War.
She said she was looking forward to her first visit to Northern Ireland as president and that she would foster an inclusive dialogue across the island.
Connolly was elected in a landslide vote at the end of October - defeating Fine Gael candidate Heather Humphreys.
The 68-year-old takes over the role from Michael D Higgins, whose 14-year term ended at midnight.
The inauguration ceremony was attended by politicians, judges and other invited guests took place at Dublin Castle.
We can and should take real pride in the success of the Good Friday Agreement model of peaceful resolution of conflict, she said.
Taoiseach Micheál Martin congratulated Connolly on assuming office saying it was a happy and momentous day for her and her family.
The Republic of Ireland's president is the country's head of state, however it is a non-executive role.
Connolly's inaugural journey from Farmleigh at Phoenix Park to Dublin Castle was marked by a ceremonial motorcade, followed by a swearing-in ceremony in St Patrick's Hall.
A service of prayer and reflection took place during the ceremony, which included a speech by Connolly.
Who attended the inauguration?
In addition to the Taoiseach, senior Irish government ministers and judges attended the inauguration. Northern Ireland's First Minister Michelle O'Neill also attended the ceremony, accompanied by Sinn Féin president Mary Lou McDonald.
Connolly has served as a TD (member of Irish parliament) since 2016 and her election as president will trigger a by-election in Galway West. She previously worked as a barrister and psychologist.
