Diodotus II was a Greco-Bactrian king, son of Diodotus I.
He is known for concluding a peace with the Parthians (Justin l.c.), in order to forestall the Seleucid reconquest of both Parthia and Bactria.
Around 230 BC, Diodotus II was killed by an usurper, Euthydemus I, founder of the Greco-Bactrian Euthydemid dynasty (Polyb. xi. 34, 2).