This study hypothesized that oxidative stress in women with diminished ovarian reserve (DOR) can influence in vitro fertilization (IVF) outcomes. Therefore, we investigated the effect of intraovarian platelet-rich plasma (PRP) administration on the oxidative stress state in follicular fluid in DOR patients. Following the follow-up of a retrospective cohort study, follicular fluid was isolated from twenty-five DOR patients. The total antioxidant capacity (TAC), catalase (CAT), and superoxide dismutase (SOD) activities, total oxidant status (TOS), and malondialdehyde (MDA) levels were measured before and after intraovarian PRP administration using colorimetric methods. The levels of estradiol (E2), anti-mullerian hormone (AMH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were measured at baseline and after two menstrual cycles. The quantity and quality of oocytes and embryos were assessed at both stages. Following intraovarian PRP injection, an increase in TAC levels, elevated CAT and SOD activities, and a decline in TOS and MDA content in the follicular fluid of DOR women were observed. AMH and E2 hormone levels also increased post-treatment. Additionally, a relative increase in the number and quality of oocytes and embryos was observed after a single PRP injection. Intraovarian PRP injection improves the oxidative state of follicular fluid and potentially enhances IVF outcomes in DOR women.