Leo Varadkar has become the Republic of Ireland's new taoiseach (prime minister).
A parliamentary vote on Wednesday confirmed the 38-year-old as the country's youngest and first gay leader by 57 votes to 50, with 45 abstentions.
The former GP, who is the son of an Irish nurse and a doctor from India, won the Fine Gael party leadership earlier this month.
He has made his leadership rival Simon Coveney the deputy leader of the party.
'New European centre'
Addressing the Dáil (Irish parliament) after his election, Mr Varadkar said: "I've been elected to lead but I promise to serve."
"The government that I lead will not be one of left or right because those old divisions don't comprehend the political challenges of today.
"The government I lead will be one of the new European centre as we seek to build a republic of opportunity."
Mr Varadkar then travelled to the president's residence, Áras an Uachtaráin, where President Michael D Higgins gave him the seals of office to officially confirm his appointment.
His first job as taoiseach has been to announce the members of his government.
Among the first of the new cabinet appointments was Charlie Flanagan to the role of justice minister, moving from his post as foreign affairs minister.
'Diverse and inclusive'
Former Taoiseach Enda Kenny nominated Mr Varadkar to succeed him at the start of Wednesday's Dáil proceedings, saying he would carry out the role with integrity and skill.
"As the country's youngest holder of this office, he speaks for a new generation of Irish women and Irish men," he said.
"He represents a modern, diverse and inclusive Ireland and speaks for them like no other, an Ireland in which each person can fulfil their potential and live their dreams."
Sinn Fein President Gerry Adams wished Mr Varadkar well in his new role.
"I think he is a decent man. I wish him well," he said.
"I do not know him well - although he and I once attended the same Pilates class.
"We couldn't get the former taoiseach to stretch as far as that," Mr Adams added.
Mr Varadkar acknowledged the joint exercise class.
He jokingly added that Mr Adams had been much better at Pilates because "he has greater experience of being in a tight squeeze."
The European Commission President Jean-Claude Juncker, also congratulated the new taoiseach, emphasising the common challenge posed by Brexit.
"I am confident that we will develop a close working relationship to tackle the various challenges facing Ireland and the European Union that lie ahead, including the consequences of the decision of the UK to leave the EU," Mr Juncker said.
Who is Leo Varadkar?
The former GP is the son of an Irish nurse and a doctor from India.
He was first elected as a councillor at the age of 24 and took a seat in the Dáil in 2007.
Shortly before the 2015 same-sex marriage referendum in Ireland he came out as gay during an interview with RTÉ.
His views are regarded as a centre-right politically due to his approach to socio-economic issues.
In 2011, Fine Gael appointed Mr Varadkar as the minister for transport, tourism and sport - and then health minister.
More recently he has overseen Ireland's welfare system.
Mr Kenny was the longest serving Fine Gael taoiseach and the first to serve two terms.
He made his final speech to the Dáil on Tuesday, stating that he had always strived to get the best for the Irish people.
'Re-energise the party'
Mr Varadkar not only takes over the role of taoiseach, but also its main challenges, including the implications of Brexit on Ireland and the collapse of devolved government in Northern Ireland.
Due to his sexuality and ethnic background, he is seen by many as a liberal leader of a country once perceived as socially conservative.
Shortly after he addressed Fine Gael for the first time since being leader, Leo Varadkar tweeted that he was "delighted" to appoint housing minister Simon Coveney as his deputy.
He added that together they would "guide Fine Gael's role in government and re-energise the party".