This study evaluated the production of marine biodegradable plastics, specifically polyhydroxyalkanoates (PHAs), using waste paper from food containers as a novel material source. The results showed that adding dilute sulfuric acid as a pretreatment may have a negative impact on enzyme hydrolysis efficiency. Without pretreatment, the highest glucose concentration was observed in the 50-min heating group. In the experimental group with 1% dilute sulfuric acid as a pretreatment, the highest average glucose concentration was observed in the 25-min treatment group. In flask scale experiments, the C/N ratio was controlled at 10, 20, and 30. The results showed that when the C/N ratio was 10, the PHA/CDM ratios were 16.3 and 23.6 at 48 and 72 h, respectively. After 96 h of cultivation using hydrolysis liquid from the waste paper container as the sole carbon source in a 5-L scale experiment, the PHA/CDM ratio was 28.7 and the PHA concentration was 0.95 g/L. The potential bacterial strain in this study was confirmed to be a Bacillus genus bacterium after strain identification. The signal peaks indicated that the PHA obtained from the Bacillus sp. production process was PHB.