The Bishop of Truro, the Right Reverend Tim Thornton, has taken his seat in the House of Lords.
He was flanked by the Bishops of Exeter and Worcester as he swore his oath of allegiance to the Queen.
Bishop Thornton, 56, replaces the former Bishop of Manchester, the Right Reverend Nigel McCulloch, who retired in January.
He has been Bishop of Truro since 2009, having previously been area bishop of Sherborne since 2001.
There are 26 places reserved for Bishops in the Lords – the two archbishops and the bishops of London, Winchester and Durham get automatic seats and are joined by the 21 longest serving diocesan bishops.
Bishop Thornton, known to all in the diocese as Bishop Tim, became the 15th Bishop of Truro when he took up the post.
He succeeded popular Bill Ind, known as Bishop Bill, who retired the previous year.
Bishop Tim was born in Leeds and educated at Devonport High School for Boys when his father was vicar of St Alban's Church in Plymouth.
He took an honours degree in Theology at Southampton University and trained for the priesthood at Oxford, later working in London, Wakefield and Cardiff, before taking up the post of Bishop of Sherborne.
His wife Sian is a primary school teacher and the couple have a 25-year-old son living in London, and a 20-year-old daughter studying at Leeds University.
Bishop Tim has not been afraid to voice his concerns on controversial matters of the day, and earlier this year said the Government still has "very important questions" to answer on the "complex" issue of same-sex marriage.
After co-chairing a meeting on the subject with Truro and Falmouth Conservative MP Sarah Newton, Bishop Tim said he was "personally against the idea" but added that the two sides "have to try and find a way forward".
He has also spoken of his belief that the greatest threat to Christianity is a lack of confidence in the faith saying: "My biggest concern is that Christians are not willing or able to bear witness to the faith that they believe.
"Yes, there are many outside threats to us – there always will be – but if we believe what the gospel says then we ought to have the confidence in what we believe."
Bishop Tim, who is chairman of the Children's Society, also declared his optimism for the future of religion in Britain.