Transferred use of the surname, in origin a local name from the city of Chester, so called from an Old English form of Latin castra ‘legionary camp’. Use as a given name has become quite common since the 20th century.
English and Scottish: patronymic from the personal name John. As an American family name, Johnson has absorbed patronymics and many other derivatives of this name in continental European languages. (For forms, see Hanks and Hodges 1988.)