Born on 7 December 1947 in Dannevirke, McGibbon was educated at Victoria University of Wellington. He earned a Bachelor of Arts in 1968, Honours the following year and in 1971, he graduated with a Master of Arts degree with distinction, majoring in history.[1]
His career as a historian began with an appointment in 1971 as the Defence Historian at the Ministry of Defence, where he worked for eight years. In 1979, he started work for the Department of Internal Affairs in the Historical Publications Branch.[1] From 1982, he was the only staff member dealing with military history and produced the official history of New Zealand's involvement in the Korean War.[2] In 1994 he earned a Doctor of Letters, also from Victoria University.[1] He later was General Editor (War History) at the Ministry for Culture and Heritage.[3] His primary areas of interest are New Zealand's diplomatic and military history, with particular focus on New Zealand's involvement in 20th-century warfare.[1]
In the 1997 Queen's Birthday Honours, McGibbon was appointed an Officer of the New Zealand Order of Merit, for services to historical research.[4] From 2010 to 2014, McGibbon was New Zealand's representative in the tri-nation Joint Historical and Archaeological Survey of the Anzac Battlefield, working alongside historians and archaeologists from Australia and Turkey; he was a co-editor of Anzac Battlefield: A Gallipoli Landscape of War and Memory, the resulting publication from the Cambridge University Press.[5]
Since 1981 he has been managing editor of the New Zealand Institute of International Affairs' journal New Zealand International Review.