Andronicus III Palaeologus (c. 1296 - June 15, 1341), Byzantine emperor, was the son of Michael, son of Andronicus II.

His conduct during his youth was so violent that, after the death of his father Michael in 1320, his grandfather resolved to deprive him of his right to the crown. Andronicus rebelled; he had a powerful party, and the first period of civil war ended in his being crowned and accepted as colleague by his grandfather, 1325. The quarrel broke out again and, notwithstanding the help of the Bulgarians, the older emperor was compelled to abdicate in 1328.

His chief minister during this period was John Cantacuzenus, later Emperor John VI. During his reign Andronicus III was engaged in constant war, chiefly with the Ottoman Turks, who greatly extended their territory, conquering almost all of Asia Minor. Under Andronicus's rule, Nicaea fell to Ottoman emir Orhan I in 1331, with Nicomedia following in 1337. He annexed large regions in Thessaly and Epirus, but they were lost before his death to the rising power of Serbia under Stefan Dusan. Andronicus worked on the reorganization of the navy, and recovered Lesbos and Chios from the Genoese. He died in 1341, and was succeeded by his son, John V.