Let (V, ) be a symplectic vector space and let φ : M → V be a symplectic immersion. We show that φ(M) ⊂ V is locally an extrinsic symplectic symmetric space (e.s.s.s.) in the sense of Cahen et al. (J Geom Phys 59(4):409fb-425, 2009) if and only if the second fundamental form of φ is parallel.Furthermore, we show that any symmetric space, which admits an immersion as an e.s.s.s., also admits a full such immersion, i.e., such that φ(M) is not contained in a proper affine subspace of V , and this immersion is unique up to affine equivalence. Moreover, we show that any extrinsic symplectic immersion of M factors through to the full one by a symplectic reduction of the ambient space. In particular, this shows that the full immersion is characterized by having an ambient space V of minimal dimension.