She was the daughter of famed poet Lord Byron (Byron, George Gordon Byron, 6th Baron) and Annabella Milbanke Byron, who legally separated two months after her birth. Her father then left Britain forever, and his daughter never knew him personally. She was educated privately by tutors and then self-educated but was helped in her advanced studies by mathematician-logician Augustus De Morgan (De Morgan, Augustus), the first professor of mathematics at the University of London. On July 8, 1835, she married William King, 8th Baron King; and, when he was created an earl in 1838, she became countess of Lovelace.

She became interested in Babbage's machines as early as 1833 and, most notably, in 1843 came to translate and annotate an article written by the Italian mathematician and engineer Luigi Federico Menabrea, "Notions sur la machine analytique de Charles Babbage" (1842; "Elements of Charles Babbage's Analytical Machine" ). Her detailed and elaborate annotations (especially her description of how the proposed Analytical Engine could be programmed to compute Bernoulli numbers) were excellent; “the Analytical Engine,” she said, “weaves algebraic patterns, just as the Jacquard-loom weaves flowers and leaves.”