Post-harvest losses remain a major challenge to food security, farm income, and agricultural sustainability in northern production zones like Kano State, Nigeria. The magnitude, causes, critical loss points, and economic implications of post-harvest losses among rice, maize, sorghum, millet, tomato, cabbage, and onion was assessed in Kano State. Quantitative descriptive survey design was used; data were collected between May and October 2025, covering wet and dry agricultural production seasons from 1,700 respondents across 40 Local Government Areas using a structured questionnaire administered through Computer-Assisted Personal Interviewing with the Open Data Kit platform. Respondents estimated losses at storage, transportation, processing, marketing, and consumption stages as proportions of harvested or produce handling. Data were summarized using frequencies, percentages, means, and comparative descriptive statistics in SPSS Version 25. Tomato recorded the highest average storage loss (43.7%), transportation loss (41.3%), processing loss (37.7%), and marketing loss (38.3%). Onion recorded the highest average consumption-stage loss (34.0%). Major causes included insufficient storage capacity (77.38%), inadequate pest control (76.09%), poor warehouse management (74.80%), over-supply leading to spoilage (73.20%), and inadequate market information (71.36%). Percentage revenue losses were highest for cabbage (29.33%), tomato (27.61%), and onion (26.30%). In absolute monetary terms, maize recorded the largest average revenue loss (₦438,149.9), despite its lower percentage revenue loss of 13.99%. The findings indicate that perishable vegetables face the greatest proportional losses, while high-volume cereal production can generate substantial absolute economic losses even at lower percentage loss rates. The study recommends targeted improvements in storage, transportation, handling, market information, and supply-chain coordination.