Background: Hypertensive disorders during pregnancy pose a significant public health problem with serious consequences for maternal and fetal health. Women with a good knowledge of pregnancy hypertension are more likely to promptly report symptoms and seek medical attention. In addition, self-care knowledge can effectively prevent or control blood pressure during pregnancy. Objectives: This study evaluated primiparous women’s knowledge of pregnancy blood pressure disorders and self-care by providing video education. Methods: In this quasi-experimental study, 84 primiparous mothers in Dezful City, Iran, within June to September 2023 were divided into two intervention and control groups based on the multistage sampling technique. Knowledge and self-care questionnaires regarding pregnancy hypertension were sent to both groups before and after the intervention. Education was provided through video education. The data were analyzed using frequency, percentage, mean, standard deviation, and independent and paired t-tests. Results: Video education increased the intervention group’s knowledge of hypertensive disorders of pregnancy (pre = 9.76 ± 3.42; post = 16.83 ± 3.74; P < 0.001) and self-care (pre = 50.66 ± 10.63; post = 54.07 ± 8.67; P < 0.001). However, knowledge (pre = 8.35 ± 3.36; post = 8.87 ± 3.58; P = 0.519) and self-care related to pregnancy blood pressure (pre = 50.36 ± 2.79; post = 50.30 ± 10.92; P = 0.833) in the control group did not change before and after the intervention. Conclusions: Using educational videos can improve mothers’ knowledge regarding pregnancy blood pressure and preventive self-care.