Kornicki was born at Maidenhead on 1 May 1950, the eldest son of Sq/Ldr Franciszek Kornicki and Patience Ceredwin Kornicka (née Williams). He went to schools in Malta, Aden and Cyprus and was then educated at St George's College, Weybridge. He matriculated at Lincoln College, Oxford, initially to read Classics. He graduated with First Class Honours in Japanese with Korean in 1972. He spent the academic year 1972-3 as a Japanese Ministry of Education foreign student at Tokyo University of Education (now Tsukuba University) and then returned to Oxford and in 1975 received an MSc in Applied Social Studies. He then moved to St Antony's College, Oxford to begin work on a DPhil on Japanese literature of the Meiji period. In 1976 he was awarded a Japan Foundation fellowship for study in Japan and spent 18 months at the Research Institute for the Humanities at Kyoto University, studying under Professors Asukai Masamichi and Yoshida Mitsukuni. He taught Japanese at the University of Tasmania from 1978 to 1982, and was subsequently an associate professor at the Research Institute for the Humanities at Kyoto University. In 1985 he came to Cambridge, where he has been a fellow of Robinson College since 1986, and Deputy Warden since 2008. He was President of the European Association for Japanese Studies (EAJS) in 1997-2000.
The Book in Japan: A Cultural History from the Beginnings to the Nineteenth Century, Leiden: Brill, 1998. Paperback, University of Hawaii Press, 2000. ISBN 978-0-8248-2337-5
Early Japanese Books in Cambridge University Library: A Catalogue of the Aston, Satow and von Siebold Collections, with N. Hayashi (Cambridge University Press), pp. xx + 520, 1991 ISBN 978-0-521-36496-6