Alkali metals in ionic compounds are conventionally regarded as electron donors, forming the basis of the classical ionic paradigm. Under extreme compression, however, this picture becomes questionable. Here we combine first-principles calculations and CALYPSO structure prediction to investigate K-Te, Rb-Te, and Cs-Te compounds over 0–800 GPa. We find that pressure activates the $d$ orbitals of heavy alkali metals, enabling strong hybridization with Te $5p$ states and significant band broadening, which drives a redistribution of electronic occupation between $p$ and $d$ manifolds. As a result, the alkali metals progressively lose their donor character and evolve toward an anion-like state characterized by enhanced electron accumulation. The decreasing reversal pressure from K to Cs arises from the combined effects of intrinsic electronic characteristics and pressure-induced structural evolution, where the formation of favorable high-pressure structures with shorter metal-Te distances and stronger orbital overlap promotes metal $d$-state participation and $p\text{−}d$ hybridization. These results reveal that pressure-induced $d$-orbital activation and competitive $p\text{−}d$ occupancy provide an intrinsic mechanism for tuning charge polarity in closed-shell ionic systems, leading to orbital-selective electronic reconstruction.

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• Chemical charge transfer
• Electronic structure
• High-pressure studies
• Pressure effects
• Alkali metals
• Density functional calculations