Reynolds was awarded the Wolfson History Prize, 2005, and elected a Fellow of the British Academy in 2005. His research and writing specialise in the two world wars and the Cold War. He served as Chairman of the History Faculty at Cambridge in 2013-15 and retired from University teaching in 2019. He has served on academic advisory boards for the redevelopment of the Imperial War Museum First World War Galleries (2011-14) and Second World War Galleries (since 2016).[3] In 2021, he succeeded Roger Knight as President of Cambridge University Cricket Club.
Reynolds has made thirteen documentaries on 20th-century history for the BBC, most recently the three-part BBC2 series Long Shadow, based on his award-winning book about the legacies and memory of 1914–18 and a trilogy of films about the Big Three allies in the Second World War: World War Two: 1941 and the Man of Steel, World War Two: 1942 and Hitler's Soft Underbelly and World War Two: 1945 and the Wheelchair President. All these films have been directed by Russell Barnes.[4]
Reynolds was also the writer and presenter of the award-winning ninety-part series America, Empire of Liberty, broadcast on BBC Radio 4.
Reynolds is married, with one son and three grandchildren.[5]
1981: The Creation of the Anglo-American Alliance, 1937–1941: a Study in Competitive Co-operation (1981) University of North Carolina Press ISBN0-8078-1507-1 (Awarded the Bernath Prize by the Society for Historians of American Foreign Relations, 1982)
1988: An Ocean Apart: the Relationship between Britain and America in the 20th Century – co-author David Dimbleby. Hodder & Stoughton ISBN0-340-40666-6 (Linked to BBC/PBS TV series.)
1991: Britannia Overruled: British Policy and World Power in the 20th Century. Longman ISBN0-582-43725-3
1994: Allies at War: the Soviet, American and British Experience 1939–1945 (Franklin and Eleanor Roosevelt Institute Series on Diplomatic and Economic History). (Co-edited with Warren F. Kimball and A. O. Chubarian). Palgrave Macmillan ISBN0-312-10259-3
1994: The Origins of the Cold War in Europe: International Perspectives (editor). Yale University Press ISBN0-300-05892-6
1995: Rich Relations: the American Occupation of Britain, 1942–1945. Random House ISBN0-517-16871-5 (Awarded the US Society for Military History's Distinguished Book Award, 1996)
2000: One World Divisible: a Global History since 1945.. Allen Lane ISBN0-7139-9461-4
2004: In Command of History: Churchill Fighting and Writing the Second World War. Random House ISBN0-679-45743-7 (Awarded the Wolfson History Prize, 2004)
2016: Transcending the Cold War: Summits, Statecraft, and the Dissolution of Bipolarity in Europe, 1970–1990. (Co-edited with Kristina Spohr) Oxford University Press ISBN978-0-19-872750-7
2018: The Kremlin Letters: Stalin's Wartime Correspondence with Churchill and Roosevelt, with Vladimir Pechatnov. Yale University Press ISBN978-0-300-22682-9 (Awarded the Link-Kuehl Prize by the Society for Historians of American Foreign Relations, 2020)
2019: Island Stories: Britain and its History in the Age of Brexit HarperCollins ISBN978-0-00-828231-8
2023: Mirrors of Greatness: Churchill and the Leaders Who Shaped Him HarperCollins ISBN978-0-00-843991-0
2008: Armistice – BBC2 (Grierson Award: Best Historical Documentary, runner-up)
2008–09: America, Empire of Liberty – BBC Radio 4 (90-part series, accompanying the writer's 2009 book)[7][8] (Voice of the Listener & Viewer Award for the Best New Radio Programme of 2008; Sony Radio Academy Award, Nomination, 2009; Orwell Prize, Shortlist, 2010)