John III of Isenburg-Büdingen-Birstein (German: Johann III. von Isenburg-Büdingen-Birstein) was the Count of Isenburg-Büdingen-Birstein from 1511 until 1533. John was a son of Louis II of Isenburg-Büdingen. After Louis died in 1511, John and his brothers partitioned his territory, but from 1517 became involved in a war. John died in 1533 and was succeeded by his three sons Reinhard, Philip, and Louis III.