This systematic review examines how ChatGPT influences university students' critical and creative thinking by synthesizing 67 empirical studies (2022-2025) following PRISMA guidelines. We applied a dual-lens framework distinguishing convergent (critical thinking) and divergent (creative thinking) processes. Analysis revealed that, ChatGPT supports cognitive development when embedded within inquiry-oriented and scaffolded instructional designs, especially through processes such as metacognitive regulation, argumentative reasoning, and idea generation, which in turn produce synergistic gains across both critical and creative domains. However, in unstructured contexts, researchers observed asymmetrical patterns favoring creativity over critical thinking and joint declines across domains, both of which often triggered cognitive offloading. These findings highlight that ChatGPT's cognitive effects are contingent on pedagogical framing. We recommend embedding explicit scaffolds—such as reflective prompts, rubric-guided evaluation, and AI-literacy training—to harness ChatGPT's potential as a dialogic partner rather than a convenience tool. Implications for instructional design involve co-activating critical and creative processes through recursive inquiry tasks and multi-source feedback loops. This review informs educators and researchers on designing AI-mediated learning environments that promote higher-order thinking while mitigating risks of dependency and reduced epistemic engagement.