Background: Ethiopia is the homeland of various crops due to its diverse and suitable agro-ecological zones. As a result, smallholder farmers grow multiple crops on a small piece of land both for consumption and commercial purposes in different portions of Ethiopia, including the northwestern part of the country. However, crop diversification status and extent of farmers were not well understood. Therefore, this study examined determinants of crop diversification in a pepper-dominated smallholder farming system in northwest Ethiopia. Methods: Primary data was collected through a semi-structured interview schedule administered on 385 crop producers selected using a systematic random sampling technique. Moreover, the survey was supplemented by using secondary data, focus group discussions, and key informant interviews. Methods such as the descriptive, inferential statistics, and econometrics model were used for analyzing the data. Results: The average crop diversification index was 0.77, and most smallholder farmers (92.46%) used crop diversification as a strategy for risk reduction, nutritional improvement, consumption, and commercial needs. Moreover, the Tobit model result revealed that the status and intensity of crop diversification were significantly influenced by farmland, sex, age, land fragmentation, distance to development center, market distance, and non-/ off-farm income participation. Conclusion: Generally, most farm households used crop diversification as a norm and best strategy for minimizing risk, income source, nutritional and livelihood improvement. Therefore, crop producers, agricultural experts, the Ethiopian government, and partner organizations should give special attention to extension service, market, and infrastructure development to enhance the role of agricultural diversification for households.