As the ceremony began, Welby promised he would "promote unity, peace and love among all Christian people," The Guardian reported. After it was over, he reaffirmed his opposition to gay marriage, which comes up for a vote Tuesday in Parliament.
Welby, 57, was selected to succeed Archbishop Rowan Williams as the senior bishop of the Church of England and head of the Anglican Communion in November after little more than a year as bishop of Durham. He decided to become an Anglican priest in his 30s after several years as an oil company executive.
His predecessors include St. Augustine of Canterbury, the first archbishop, who reigned in the early 7th century; St. Thomas Becket, killed in the cathedral by King Henry II's knights; and Thomas Cranmer, who supported King Henry VIII's break with the pope and was burned at the stake for treason and heresy under Henry's daughter, Mary I.
Welby will be enthroned next month at Canterbury Cathedral.
"I stand, as I have always stood over the last few months, with the statement I made at the announcement of my appointment, which is that I support the Church of England's position on this," Welby said when asked about the bill to legalize same-sex marriage.
Asked about the move to Lambeth Palace, the archbishop's residence in London, Welby said he and his family are "getting lost a lot."