The Datça and Bozburun are E–W-oriented peninsulas located near the Pliny–Strabo Trench Zone and considered to be eastern continuations of the seismically-active Hellenic Subduction Zone. Although no catastrophic earthquakes were recorded on the peninsulas in the previous century, two large earthquakes of a magnitude of 6.6 (Mw) occurred in the Gulf of Gökova in the north, in 2017, and a magnitude of 7.1 (Mw) in the Gulf of Fethiye in the south was recorded in 1957. Therefore, the necessity to pay close attention and issue warnings regarding potential earthquakes in and around the peninsulas has been increasing. Inversion of fault slip vectors affecting both the Plio–Quaternary and Paleozoic units in the Datça and Bozburun Peninsulas yields N–S, NE–SW, and NW–SE extensional stress states. The NW–SE trending Datça Basin formed during the Plio–Quaternary under the NE–SW extensional regime. The inversion of the focal mechanisms for shallow earthquakes in the Datça and Bozburun Peninsulas provides N–S and NW–SE extensional stress states. Extensional stress tensors obtained from both the fault planes measured, as well as the focal mechanisms of the shallow earthquakes, are related to the roll-back process of the African slab along the Hellenic Subduction Zone.