1610s, "not dependent on something else," from in- (1) "not, opposite of" + dependent. French independant is attested from c. 1600; Italian independente from 1590s. In English originally of churches, nations; in reference to persons from 1660s. Meaning "able to live well without labor" is from 1732. Meaning "unbiased, set up so as to be unaffected by outside influence" is from 1790. Related: Independently.
As a noun, from 1640s as "member of an independent congregational church, English Congregationalist." It is attested from 1670s as "one who acts according to his own will" and 1808 in the specific sense "person not acting as part of a political party."