(French) feminine form of Michel, the French form of Michael. This name is now also used extensively in the English-speaking world. It was popular in the 1970s and 80s, possibly influenced in part by a Beatles song with this name as its title (1966).
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.)