We show that large classes of non-arithmetic hyperbolic n-manifolds, including the hybrids introduced by Gromov and Piatetski-Shapiro and many of their generalizations, have only finitely many finite-volume immersed totally geodesic hypersurfaces. In higher codimension, we prove finiteness for geodesic submanifolds of dimension at least 2 that are maximal, i.e., not properly contained in a proper geodesic submanifold of the ambient n-manifold. The proof is a mix of structure theory for arithmetic groups, dynamics, and geometry in negative curvature.