This study investigated the effects of plagiarism detection software on the originality of project writing among final-year students in tertiary institutions in Ekiti State, Nigeria. The primary objective was to examine how the use of plagiarism detection tools influences students’ writing originality, understanding of intellectual property rights, and citation practices. The study adopted a descriptive survey research design, with a population comprising all final-year students in selected tertiary institutions within the state. A sample of 300 students was randomly selected for the study. Data were collected using a structured questionnaire titled “Plagiarism Detection and Academic Originality Questionnaire (PDAOQ)”. The collected data were analyzed using descriptive statistics (mean and standard deviation) and the Pearson Product Moment Correlation (PPMC) to test the hypotheses at a 0.05 level of significance. The findings revealed that the use of plagiarism detection software such as Turnitin and Grammarly significantly enhances students’ originality in project writing and improves their understanding of citation and intellectual property rights (r = 0.871, p < 0.05). The study further established that plagiarism detection tools promote academic integrity by enabling students to identify and correct unintentional plagiarism. Nonetheless, challenges such as high software costs, inadequate user training, and technical issues were identified as barriers to effective utilization. The study concluded that plagiarism detection software plays a crucial role in fostering academic honesty, improving research quality, and enhancing writing competence among students. It was recommended that tertiary institutions in Ekiti State should integrate plagiarism detection tools into their academic curriculum, organize regular training workshops for students and lecturers, and establish clear institutional policies governing their use.