Spin qubits in silicon quantum dots (QDs) are promising for realization of large-scale qubit systems, thanks to their scalability. However, there are challenges to be overcome for the realization, such as problems on the interface between the qubit chip and peripheral control circuitry. Interposers are expected to serve as a viable solution for the interface for silicon qubits. In this paper, we report DC and RF characterizations of a QD on an interposer at cryogenic temperatures. The results show the possibility of cryogenic interposer integration of spin qubits and peripheral control circuitry.