In this Letter we begin the study of visible dark sector signals coming from binary neutron star mergers. We focus on dark photons emitted in the 10 ms-1 s after the merger, and show how they can lead to bright transient γ-ray signals. The signal will be approximately isotropic, and for much of the interesting parameter space will be close to thermal, with an apparent temperature of ∼100 keV. These features can distinguish the dark photon signal from the expected short γ-ray bursts produced in neutron star mergers, which are beamed in a small angle and nonthermal. We calculate the expected signal strength and show that for dark photon masses in the 1-100 MeV range it can easily lead to total luminosities larger than 10^{46} ergs for much of the unconstrained parameter space. This signal can be used to probe a large fraction of the unconstrained parameter space motivated by freeze-in dark matter scenarios with interactions mediated by a dark photon in that mass range. We also comment on future improvements when proposed telescopes and midband gravitational detectors become operational.