The present study attempted to find out the usefulness and effectiveness of sentence combining strategy as a method for helping students combine clauses into one meaningful sentence and construct more syntactically mature sentences. This is initiated to help the students improve their writing performance in English and make sentence construction in writing more automatic and less labored. This study utilized a one-group pretest–posttest design. This method permitted the researcher to have a good view of how the writing skills of the selected grade 9 students at Sta. Catalina Integrated National High School can be improved by employing Sentence Combining Strategy and Writing Performance in English. Using coordinating conjunctions, combining independent clauses into one meaningful sentence, and revising and rearranging jumbled clauses into paragraphs were the Sentence Combining Strategies utilized by the researcher to improve the writing performance of the respondents. More so, lesson exemplars, pretest, and posttest were the instruments used in this study. The development, validity, and reliability of these finalized instruments were checked and evaluated by the experts prior to their utilization. The result of the study determined that there is a significant difference between the pretest and post-test scores of the respondents in their writing performance before and after using the sentence combining strategy. This implies that the sentence-combining strategy has a positive impact on the students writing performance. Therefore, this study assumed that Sentence Combining Strategy is a great tool to improve the literacy skills and writing performance of the selected grade 9 students in Sta. Catalina Integrated National High School.