In the present contribution, starch/poly(l-lactic acid) (PLA) hybrid foams were prepared by baking a mixture of starch, PLA, and other ingredients in a hot mold. The effects of conditioning relative humidity, conditioning storage time, and PLA content on moisture and water absorption, mechanical properties, and biodegradability of the as-prepared hybrid foams were investigated and the results were compared with those of the pure starch foams. Moisture absorption for both starch and starch/PLA foams was found to increase with increasing conditioning relative humidity level (the storage condition was 25 °C for 7 days) and conditioning storage time (the storage condition was 42% RH and 25 °C). Addition of PLA helped promote the resistance to water absorption of the hybrid foams. In all of the testing conditions investigated, the ultimate tensile strength was found to be a maximum when the relative humidity was 42% RH (for a fixed storage period of 7 days) and when the storage period was 2 days (for a fixed relative humidity of 42% RH). The loss of crispness of the starch-based foams was found to occur at the moisture content of around 7–9%. Addition of PLA improved the ultimate tensile strength and the elongation at break of the composite foams. Lastly, the enzymatic degradability of both starch and starch/PLA foams by α-amylase was found to increase with increasing reaction time and addition of PLA resulted in the hybrid foams being less subservient to enzymatic degradation by α-amylase than pure starch foams, especially for ‘long’ reaction times.