Abstract: Potassium high-efficiency vegetable soybeans have a higher absorption and utilization efficiency of potassium and stronger potassium uptake capabilities. However, it is unclear whether their roots enhance the bioavailability of soil potassium through efficient activation, thereby ensuring potassium supply. We conducted a compartmented rhizobox experiment to compare the differences of available and slow-acting potassium in rhizosphere and non-rhizosphere soils at different distances (0 - 2 mm, 2 - 4 mm, and >4 mm) for K high-efficiency and K low-efficiency vegetable soybeans under two conditions, i.e. no potassium fertilizer application (K0) and normal potassium application (120 kg∙hm⁻²K₂SO₄, K120). The results show that, compared to the K low-efficiency variety L7, the K high-efficiency variety L20 exhibits a lower available potassium concentration in rhizosphere and non-rhizosphere soils at different distances with no-potassium fertilization, while the concentrations of slow-acting potassium are higher, especially in the >4 mm non-rhizosphere soil. This indicates that the roots of the K high-efficiency vegetable soybean L20 could utilize lower concentrations of potassium and have a stronger ability to activate slow-acting potassium. Under no-potassium fertilization condition, the K high-efficiency variety L20 has a lower ratio of available potassium to slow-acting potassium (A/S) in rhizosphere and non-rhizosphere soils with higher concentration of slow-acting potassium in rhizosphere and non-rhizosphere soils. Furthermore, no potassium application has slight impact on the dry matter and potassium accumulation in the K high-efficiency variety L20. Strong capacity in activating the transformation of slow-acting potassium into available potassium might be a substantial basis for the potassium supply in K high-efficiency vegetable soybean L20. These findings provide important theoretical basis for the breeding of K high-efficiency vegetable soybean varieties.