Background: Preeclampsia (PE) affects 2-8% of pregnancies worldwide, leading to maternal and fetal complications such as abruptio placentae, renal failure, and HELLP syndrome. Objective: To investigate the association between plasma D-dimer levels and the severity of preeclampsia, along with its impact on fetomaternal outcomes. Methods: A case-control study was conducted at Dhaka Medical College Hospital from June 2021 to May 2022, enrolling 100 preeclamptic patients (50 with severe features and 50 without severe features). Participants were between 29-40 weeks of gestation. Exclusion criteria included chronic hypertension, renal/hepatic disorders, diabetes, and fetal anomalies. D-dimer levels were measured from 3 mL venous blood samples. Maternal and fetal outcomes were documented and analyzed using SPSS software. Results: The mean age of patients was 26.62 ± 3.99 years (PE without severe feature) and 27.26 ± 5.45 years (PE with severe feature). D-dimer levels were significantly higher in the severe feature group (2.91 ± 2.14 μg/mL) compared to the non-severe feature group (0.79 ± 0.45 μg/mL; p<0.005). Severe PE was associated with higher rates of postpartum hemorrhage (58.0%), HELLP syndrome (12.0%), abruptio placentae (44.0%), and fetal growth restriction (46.0%). The severe PE group also had significantly lower APGAR scores and higher NICU admissions (42.0%). Elevated D-dimer levels were significantly correlated with maternal and fetal complications, including eclampsia (p=0.020), HELLP syndrome (p=0.011), and fetal growth restriction (p=0.022). Conclusion: Elevated plasma D-dimer levels are significantly associated with the severity of preeclampsia and adverse maternal and fetal outcomes.