In this paper, we consider the received signal strength (RSS)-based indoor visible light positioning (VLP) with unknown receiving angle. A novel VLP scheme is proposed by joint estimation of the receiver coordinate and receiver characteristic vector. We equivalently convert the original estimation problem into the problem that maximizes the projection of the RSS vector on the column space spanned by the measurement matrix. The proposed scheme does not require the prior knowledge of receiving coefficient and receiving angle. To further reduce the computational complexity, we also propose an importance sampling (IS) method for solving the VLP problem. Simulation and experimental results demonstrate the robustness of the proposed scheme to the receiving coefficient and receiving angle. Specifically, experimental results show that the proposed VLP scheme achieves a stable positioning accuracy below 7 cm under different receiver tilting angles in a 60 cm × 60 cm × 150 cm space, and is not sensitive to height perturbation.