Westad has published fifteen books on international history and contemporary international affairs, including a new version of the "Penguin History of the World" (2013). He co-edited the three-volume "Cambridge History of the Cold War" (2010) with Melvyn Leffler. His "Restless Empire: China and the World since 1750" (2012) surveys the last 250 years of China's relations with the world, and "The Cold War: A World History" (2017) provides an overview of the conflict and its long-term significance. The Times Literary Supplement, making it one of its books of the year, called it "a book of resounding importance for appraising our global future as well as understanding our past."