We study interpolation properties for Shavrukov’s bimodal logic \(\textbf{GR}\) of usual and Rosser provability predicates. For this purpose, we introduce a new sublogic \(\textbf{GR}^\circ \) of \(\textbf{GR}\) and its relational semantics. Based on our new semantics, we prove that \(\textbf{GR}^\circ \) and \(\textbf{GR}\) enjoy Lyndon interpolation property and uniform interpolation property. As a consequence of our proofs, we obtain the completeness and the finite frame property of \(\textbf{GR}^\circ \) and \(\textbf{GR}\) with respect to our new semantics.