Knigge was born in Bredenbeck (now a part of Wennigsen, Lower Saxony) in the Electorate of Hanover as a member of the lesser nobility. He studied law from 1769 to 1772 in Göttingen where he became a member of Corps Hannovera. He was allegedly initiated into Freemasonry in 1772 in Kassel, where he held a position as Court Squire (hofjunker) and Assessor of the War and Domains Exchequer. In 1777 he became Chamberlain at the Weimar court.
In 1780 Knigge joined Adam Weishaupt's BavarianIlluminati and his work with the Illuminati gave the group a great deal of publicity. But in 1783 dissensions arose between Knigge and Weishaupt, which resulted in the final withdrawal of the former on 1 July 1784. Knigge could no longer endure Weishaupt's pedantic domineering, which frequently assumed offensive forms. He accused Weishaupt of "Jesuitism", and suspected him of being "a Jesuit in disguise" (Nachtr., I, 129). "And was I", he adds, "to labour under his banner for mankind, to lead men under the yoke of so stiff-necked a fellow?—Never!"
Knigge's involvement with the Illuminati, support of the advancement of human rights, and a period of serious illness led to the loss of support of his aristocratic sponsors and finally his fortune. Knigge found a measure of financial stability again with a position in Bremen in 1790. He died in Bremen in 1796.
In Germany, Knigge is best remembered for his book Über den Umgang mit Menschen (On Human Relations), a treatise on the fundamental principles of human relations that has the reputation of being the authoritative guide to behaviour, politeness, and etiquette. The work is more of a sociological and philosophical treatise on the basis of human relations than a how-to guide on etiquette, but the German word “Knigge” has come to mean “good manners” or books on etiquette.
Allgemeines System für das Volk zur Grundlage aller Erkenntnisse für Menschen aus allen Nationen, Ständen und Religionen (General System for the Public, Towards a Foundation of all Knowledge of People of all Nations, Conditions, and Religions), 1778
Der Roman meines Lebens (The Story of my Life), 1781
On the Jesuits, Freemasons, and Rosicrucians, 1781
Sechs Predigten gegen Despotismus, Dummheit, Aberglauben, Ungerechtigkeit, Untreue und Müßiggang (Six Sermons against Despotism, Stupidity, Superstition, Injustice, Mistruth, and Idleness), 1783
Geschichte Peter Clausens (The History of Peter Clausen), 1783–85
Gesammelte politische und prosaische kleinere Schriften (Collected Political and Prosaic Lesser Writings), 1784
"Essay on Freemasonry", 1784
Contribution towards the latest history of the Order of Freemasons, 1786
Bekenntnisse (Übersetzung des Rousseauschen Werks aus dem Französischen) (Confessions"–Translation of the Works of Rousseau from the French), 1786–90
Die Verirrungen des Philosophen oder Geschichte Ludwigs von Seelbergs (The Errors of the Philosopher, or Story of Ludwig von Seelberg), 1787
Philo's endliche Antwort auf verschiedene Anforderungen und Fragen, meine Verbindung mit dem Orden der Illuminaten betreffend (Philo’s Reply To Questions Concerning His Association With the Illuminati), 1788, 2012 ISBN 978-1-105-60407-2
Über den Umgang mit Menschen (On Human Relations), 1788
Geschichte des armen Herrn von Mildenberg (The Story of the Poor Herr von Mildenberg), 1789
Benjamin Noldmanns Geschichte der Aufklärung in Abyssinien (Benjamin Noldmann's History of the Enlightenment in Abyssinia), novel, 1790
Über den Zustand des geselligen Lebens in den vereinigten Niederlanden (On the Conditions of Social Life in the United Netherlands), 1790
Das Zauberschloß oder Geschichte des Grafen Tunger (The Enchanted Castle, or the History of Count Tunger), novel, 1791
"Politisches Glaubensbekenntnis von Joseph Wurmbrand" ("The Political Credo of Joseph Wurmbrand"), Essay, 1792
Die Reise nach Braunschweig, (The Journey to Brunswick), novel, 1792
Erläuterungen über die Rechte des Menschen. Für die Deutschen (Elucidations on the Rights of Men. For the Germans), 1792
"Über Schriftsteller und Schriftstellerey" ("Of Writers and Writing"), essay, 1793
Geschichte des Amtsraths Guthmann (The Story of Amtsrath Guthmann), 1794
Reise nach Fritzlar im Sommer 1794 (Journey to Fritzlar in Summer 1794), satire, 1795