The massive plastic production in Indonesia is an effort to meet the demand for the food packaging sector, which is nearly 40% of the total plastic demand. Plastics are not environmentally friendly because they are not degradable. Carrageenan-based biodegradable packaging in the form of bioplastic is an alternative, but it has disadvantages such as low resistance to water. Modified starch can be used to improve bioplastic characteristics. This research aimed to determine the application of modified starch in biodegradable packaging to its biodegradability and mechanical properties. This research is experimental which consists of primary parameters and supporting parameters. The independent variables used were modified starch (0, 1, 1.5, and 2 g). The experimental design used a completely randomized design (CRD) and data analysis using the Analysis of Variance (ANOVA) and the DMRT follow-up test. The results showed that the application of modified starch in biodegradable packaging based on carrageenan had a significant effect (p <0.05) on water resistance and the best test results were 2 g of modified starch (P3) with a water resistance value of 50.96% ± 4.86. Meanwhile, the results of biodegradability, tensile strength, and elongation were not significantly different.