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We study the relativistic Lee model on static Riemannian manifolds. The model is constructed nonperturbatively through its resolvent, which is based onthe so-called principal operator and the heat kernel techniques. It is shown that making the principal operator well defined dictates how to renormalize the parameters of the model. The renormalization of the parameters is the same in the light-front coordinates as in the instant form. Moreover, the renormalization of the model on Riemannian manifolds agrees with the flat case. The asymptotic behavior of the renormalized principal operator in the large number of bosons' limit implies that the ground state energy is positive. In 2 + 1 dimensions, the model requires only a mass renormalization. We obtain rigorous bounds on the ground state energy for the n-particle sector of the (2 + 1)-dimensional model.