Even though the concentrations of the total cadmium (Cd) in paddy soils from different countries have been reported, the exchangeable-Cd (Ex-Cd) concentrations in these soils are unknown despite its importance in agriculture. This study was conducted with a total of 5460 soil samples collected in Sri Lanka, representing six agro-climatic zones, six soil orders, and three irrigation types. The Ex-Cd concentrations in soil samples were extracted using 0.01 M CaCl2 and analyzed using an inductively coupled plasma-mass spectrophotometry. The Ex-Cd concentrations were <0.31–163 μg kg−1, with mean and median concentrations being 14.1 and 8.98 μg kg−1, respectively, which was affected by both agro-climatic and soil conditions. Samples from the Wet zone, particularly the Wet zone Low country, had higher Ex-Cd (24.1 μg kg−1) than those from the Dry zone Low country (11.6 μg kg−1). Among the soil orders, Histosols (21.3 μg kg−1) and Inceptisols (19.5 μg kg−1) had the highest Cd concentration while Vertisols had the lowest (6.3 kg−1). The irrigation types only affected Ex-Cd concentrations in Dry zone Low country, but not in other agro-climatic zones. Overall, it is important to consider agro-climatic zones, soil orders, and irrigation types when implementing agronomic strategies to mitigate the risk associated with Cd accumulation in paddy fields.