Regarding　resonance　and　converter-driven　stability,　sub-　and　super-synchronous　oscillations　(SSO　and　SPO)　occur　in　power　systems　with　high　penetration　of　IBRs.　Integrating　various　IBRs　with　complex　control　systems　presents　challenges　in　mitigating　oscillations　across　the　entire　system.　Multiple　sources,　causes,　and　frequencies　contribute　to　power　system　oscillations.　This　paper　proposes　a　deep　reinforcement　learning　(DRL)-based　robust　oscillation　mitigation　controller　integrated　with　the　STAT-COM　controller.　A　single　transmission　line　system,　comprising　both　IBR　and　STATCOM,　is　designed　to　simulate　oscillations　and　generate　cases　to　train　the　DRL　model.　The　proposed　method　is　tested　on　untrained　oscillation　cases　to　evaluate　the　robustness　of　the　controller.　As　a　result,　the　trained　DRL-based　controller　appropriately　operates　on　steady,　transient,　and　oscillating　states.　©　2025　IEEE.