Leonardo da Vinci entered professional artistic life through Andrea del Verrocchio's workshop in Florence, where painting, sculpture, and technical craftsmanship intersected. By the 1470s he was producing independent work and developing a method based on close observation, preparatory drawing, and experiment. Projects such as the Adoration of the Magi reveal the ambitions of his early painting, although several important commissions remained unfinished as his interests and patrons changed.

Around 1482 he moved to Milan and entered the service of Ludovico Sforza. He offered skills in military and civil engineering as well as painting, and worked on court entertainments, architectural problems, and designs for machines. The Virgin of the Rocks and The Last Supper belong to the Milanese phase. For the latter, painted at Santa Maria delle Grazie, he experimented with a technique that allowed slow revision but contributed to the work's rapid deterioration. A monumental equestrian memorial to Francesco Sforza reached the stage of a large model but was never cast in bronze.

After the French capture of Milan in 1499, Leonardo traveled and returned to Florence. He served briefly as an engineer for Cesare Borgia, producing maps and studying fortifications. In Florence he began the Mona Lisa and undertook the Battle of Anghiari for the city's council hall; the large mural was not completed. His drawings and notebooks developed investigations into human anatomy, water, geology, optics, flight, and mechanical motion. Dissections and comparative observation supported detailed anatomical studies, while mirror-script notes recorded both practical proposals and speculative ideas.

Leonardo later worked again in Milan and spent time in Rome before accepting Francis I's invitation to France in 1516. At Clos Lucé near Amboise he continued drawing, planning, and discussing projects until his death in 1519. His surviving completed paintings are relatively few, but their treatment of movement, expression, light, and atmosphere profoundly affected European art. The notebooks preserve an unusually extensive record of inquiry across artistic and technical subjects. Many inventions remained drawings or proposals, so his importance should not be measured by assuming that every design was built or functioned. His career joined the demands of patrons and commissions to sustained investigation of nature, with drawing serving as a tool for both invention and understanding.