This quasi-experimental study determined the effectiveness of utilizing socio-scientific issues-based instructions in acquiring the 21st century life skills in terms of flexibility, leadership, initiative, productivity, and social skills. Two sections of Grade 7 students in Malvar School of Arts and Trade, Malvar, Batangas, Philippines for the school year 2022-2023 were exposed to two different types of socio-scientific issues-based instructions, including argumentation-based learning and context-based learning in teaching Physics concepts. The researcher-made pre-test and post-test were administered to the respondents and they were matched paired according to their gender and pre-test scores. This study revealed that there exists a significant difference between the pre-test and post-test scores of each group of respondents on 21st century life skills. It was also found out that context-based learning is more effective in developing ones productivity and social skills. It has been concluded in this study that utilizing socio-scientific issues-based instructions in teaching Science can improve the students 21st century life skills.