Background: Dietary diversity is defined as the number of different foods or food group consumed over a given reference period. In developing countries, dietary diversity is a challenge for rural and urban communities especially women at reproductive age, who are vulnerable to malnutrition as maternal nutrient need increase during pregnancy and lactation. Malnourished mothers are unable to combat disease, and to feed adequate nutrients to their children and this will in turn affect the socio-economic development of the country. Since it is assumed that knowing the extent of dietary diversity is crucial to design strategy or plan to alleviate the problem. Objective: To assess the dietary diversity and associated factors among lactating mothers at Woreta town. Methods: community-based cross-sectional study design was employedinWoreta Town. Four hundred six lactating mothers were included via systematic random sampling techniques. The nature of the questioner structured. Data was entered, cleaned and then analyzed using SPSS version 20 software. Bivariable and multivariable logistic regression models were used to determine the associated factors affecting dietary diversity. Odds ratio (OR) with95%Confidence Interval (C.I) was use for measure of associations between the outcome and explanatory variables. Result: More than half of (57%) of the lactating mothers was from food insecure households. The mean of dietary diversity score was 4.8 and a total of 56.9 % lactating mothers had low dietary diversity (less than mean DDS). Educational status of mother, Meal frequency, pulses production, delivery at health center; home gardening, income generating activity, food insecurity and ante natal practice(ANC follow up) were significant association with dietary diversity. Conclusion: Lactating mother’s dietary diversity w government and other concerned bodies should design and implement multi-dimensional livelihood and health service programs towards alleviating low dietary diversity.