Since October 2013, the former bishop of St Edmundsbury and Ipswich has been supporting the Archbishop of Canterbury's work.
Bishop Nigel said: "It has been a privilege to work with this Archbishop of Canterbury in all that he has brought to the Church of England in his first four years."
As well as acting as a point of contact for bishops of the Province of Canterbury, he has also held additional responsibilities since June 2014 as Bishop to the Forces and Bishop to the Falkland Islands.
Bishop Nigel went on to say: "Among many highlights, it was wonderful to accompany the Archbishop in ground-breaking visits to His Holiness Pope Francis.
"As Bishop to the Armed Forces, I've hugely enjoyed seeing the extraordinarily varied work of the Armed Forces in places as diverse as Germany, Cyprus and the Falklands."
Paying tribute to him, Archbishop of Canterbury Most Rev Justin Welby, said he was "enormously grateful" to Bishop Nigel for his service and he described him as "a gracious and wise friend".
"His love for and service to the Church of England and the Anglican Communion have been a blessing and an inspiration, not just to me but to all of us at Lambeth Palace," he added.
Bishop Nigel's successor will be announced in April.