The circumstances surrounding Ian Squire's death, three weeks after his kidnap, were not immediately clear.
It is understood that Squire and fellow Christian charity workers David and Shirley Donovan and Alanna Carson were working as missionaries when they were abducted from their accommodation in Delta State in the south of the country in the early hours of 13th October.
A UK Foreign Office spokesman said: "We are supporting the families of four British people who were abducted on October 13 in Nigeria, one of whom was tragically killed.
"This has clearly been a traumatic time for all concerned, and our staff will continue to do all we can to support the families.
"We are grateful to the Nigerian authorities, and are unable to comment given the ongoing nature of their investigations."
In a statement, the families of the four hostages said: "Alanna, Ian, David and Shirley were kidnapped in Nigeria some three weeks ago.
"We are grateful for the support received by the British High Commission and help from the Nigerian authorities in negotiating their release.
"We are delighted and relieved that Alanna, David and Shirley have returned home safely. Our thoughts are now with the family and friends of Ian as we come to terms with his sad death.
"This has been a traumatic time for our loved ones who were kidnapped and for their families and friends here in the UK. We would therefore ask that the media respect our privacy as we come to terms with the news. We will not be making any further comment."