Generating and controlling valley-contrasting Berry curvature in two-dimensional (2D) hexagonal magnetic materials holds significant promise for advancements in spintronics and valleytronics. Here, we explore the interplay between valley index, magnetic ordering, and band topology in a single 2D semi-half-metallic system, introducing a critical state termed valley-semi-half-metal, which is crucial for realizing high Chern number quantum anomalous Hall (QAH) insulators. We identify the fluorinated $1\mathrm{T}\text{−}{\mathrm{CrS}}_2$ monolayer ($1\mathrm{T}\text{−}{\mathrm{CrS}}_2{\mathrm{F}}_2$) as a promising material, exhibiting soft ferromagnetic characteristics ideal for achieving this 2D valley-semi-half-metallic state. Remarkably, the monolayer $1\mathrm{T}\text{−}{\mathrm{CrS}}_2{\mathrm{F}}_2$ can transition from a semi-half-metallic state to a high Chern number QAH insulator with opposite-chiral edge states through magnetization reversal. Additionally, the Janus $1\mathrm{T}\text{−}{\mathrm{CrS}}_2\mathrm{FCl}$ monolayer, which lacks inversion symmetry, enables gate-tunable, valley-contrasting QAH insulator phases with opposite Chern numbers upon reversing the magnetization. Our findings highlight a promising magnetic candidate for exploring valley and topological physics, offering an alternative approach for designing switchable QAH effects and paving the way for innovative topological quantum devices.

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• Edge states
• Electronic structure
• Spin-orbit coupling
• Spintronics
• Topological insulators
• Topological phase transition
• Valley degrees of freedom
• Valleytronics