John received a diploma in Chemistry from the University of Münster in 1994. Four years later he was given a Doctor of Philosophy degree in Chemistry from the same university.
John began his career as a postdoctoral fellow at the Institute of Occupational Medicine in Münster in 1998. The same year he became a research associate at Lower Saxony Institute of Peptide Research in Hannover and held it for a year. John was a head division at the same institute from 1999 to 2000.
In 2000, Harald was appointed a researcher at PharmaCeuticals GmbH in Hannover and held the position for five years. Since 2006, he has been a senior chemist at Bundeswehr Institute of Pharmacology and Toxicology in Munich.
John is a member of German Chemical Society, American Society of Mass Spectrometry, German Society of Mass Spectrometry, Reservists Association of German Armed Forces.
On March 11, 2006 Harald John married Stefanie Pfleiderer. They have 2 children.