In this study, Sm cosputtered SiO₂ thin films were fabricated and systematically optimized for resistive random-access memory (RRAM) applications by controlling oxygen flow rate, Sm sputtering power, and sputtering time. The effects of deposition parameters on surface morphology, electrical switching behavior, endurance performance, retention characteristics, and conduction mechanisms were comprehensively investigated. Among the examined conditions, an oxygen flow rate of 6 sccm and a sputtering power of 20 W yielded the most uniform microstructure and stable bipolar switching performance. The optimized devices exhibited a clear distinction between high-resistance state (HRS) and low-resistance state (LRS), with a resistance ratio of approximately 10³. Endurance measurements demonstrated stable switching behavior over multiple cycles, while retention tests confirmed reliable data storage exceeding 10⁴ s without significant degradation. Ln(I)-Ln(V) analysis revealed that Ohmic conduction dominates in the LRS, whereas the HRS may transition to space-charge-limited current under high electric fields or nonoptimized deposition conditions. The results highlight the critical role of oxygen stoichiometry and sputtering parameters in regulating defect distribution and charge transport. This work provides a practical strategy for enhancing the stability and reliability of Sm-doped SiO₂-based RRAM devices for future nonvolatile memory applications.