Background: Nurses' leaders are protracted as high-leverage players who would be instrumental in initiating or bettering the culture of safety in the hospital, with no previous intervention done for the same in Manipur. Objectives: The aim of this study was to assess the effectiveness of an educational intervention program on patient safety culture among nurses in Manipur. Materials and Methods: A quasi-experimental study was conducted from July 2019 to December 2021 among the 32 nurses of two tertiary-level hospitals in Manipur. A structured questionnaire and Hospital Survey on Patient Safety Culture version 2 were used (Hospital Survey on Patient Safety Culture (HSOPSC) version 2.O (AHRQ, Rockyville, Maryland, USA)). A 2-day intervention based on the WHO's Multi-Professional Patient Safety Curriculum Guide was used. Data were collected before, immediately, and 3 months after the intervention. Data were summarized using descriptive using IBM SPSS 26. Paired t-test, Chi-square test, and t-test were employed to check for differences within and between the groups, and P < 0.05 was taken as statistically significant. Results: The mean knowledge scores were comparable between the groups at baseline (7.13 +/- 3.3, 8.44 +/- 3.74; P = 0.142) but differed significantly at posttest and follow-up tests (P < 0.0001). The dimensions of "staffing and work pace" and "reporting patient safety events" had the lowest positive responses from both the groups at baseline. There is a significant increase in the total safety score from baseline to posttest and follow-up in the intervention group (P < 0.001). Conclusions: The study asseverated the effectiveness of an educational intervention in increasing the knowledge and perception of patient safety culture, but the results highlighted the need for training at regular intervals.