1530s, "action, anything done," especially "evil deed," from Latin factum "an event, occurrence, deed, achievement," in Medieval Latin also "state, condition, circumstance," literally "thing done" (source also of Old French fait, Spanish hecho, Italian fatto), noun use of neuter of factus, past participle of facere "to do" (from PIE root *dhe- "to set, put"). Main modern sense of "thing known to be true" is from 1630s, from notion of "something that has actually occurred."
Compare feat, which is an earlier adoption of the same word via French. Facts "real state of things (as distinguished from a statement of belief)" is from 1630s. In fact "in reality" is from 1707. Facts of life "harsh realities" is from 1854; euphemistic sense of "human sexual functions" first recorded 1913. Alliterative pairing of facts and figures is from 1727.
Facts and Figures are the most stubborn Evidences; they neither yield to the most persuasive Eloquence, nor bend to the most imperious Authority. [Abel Boyer, "The Political State of Great Britain," 1727]
"consisting of or pertaining to facts, not fanciful or ideal," 1712, from the noun phrase matter of fact "reality as distinguished from what is fanciful or hypothetical," which is originally a legal term (1570s, translating Latin res facti), "that which is fact or alleged fact, that portion of an inquiry concerned with the truth or falsehood of alleged facts," opposed to matter of law. See matter (n.) + fact. Meaning "prosaic, unimaginative, adhering to facts" is from 1787. Related: Matter-of-factly; matter-of-factness. German Tatsache is said to be a loan-translation of the English word.
In law, that which is fact or alleged as fact; in contradistinction to matter of law, which consists in the resulting relations, rights, and obligations which the law establishes in view of given facts. Thus, the questions whether a man executed a contract, and whether he was intoxicated at the time, relate to matters of fact; whether, if so, he is bound by the contract, and what the instrument means, are matters of law. [Century Dictionary]
Factoids ... that is, facts which have no existence before appearing in a magazine or newspaper, creations which are not so much lies as a product to manipulate emotion in the Silent Majority. [Mailer, "Marilyn," 1973]
By 1988 it was being used in the sense of "small, isolated bit of true factual information."