Background Poor quality diets are the greatest obstacles to survival, growth, development, and learning in children. Dietary diversity is a major problem in developing countries including Ethiopia. For better feeding practices and focused interventions, it is essential to identify dietary diversity in children. In order to draw firm conclusions, previous studies in Ethiopia were unable to get a thorough picture of the dietary diversity among children under the age of five. Therefore, the purpose of this study was to identify minimum dietary diversity and associated factors among children under the age of five attending public health facilities in Wolaita Soddo town, Southern Ethiopia. Methods An institution-based cross-sectional study design was used from February to March, 2021. The sample size of the study was 406. A simple random sampling was used to select the study participants. The minimum dietary diversity of the children was assessed by a standardized dietary assessment tool. The information was gathered using a standardized questionnaire that was administered by an interviewer. The collected data were entered into Epi Data 4.6 then exported to SPSS 26 for analysis. A multivariable logistic regression model was used to identify the independent predictors of the study. The statistical significance level was set at P < 0.05, and the degree of the association was measured using an AOR with a 95% CI. Results A total of 399 participants were involved in this study. Nearly half (52.1%) of the study children met the minimum dietary diversity. The most popular foods were grains, roots, and tubers (79.2%), followed by dairy products (58.1%), vitamin A-rich fruits and vegetables, and grains, roots, and tubers (58.1%). Children whose mothers worked as daily workers had a lower likelihood of meeting the minimal dietary diversity requirement. However, children with separate eating plates from adults, households with food security, low monthly food expenditure, collaborative decision-making on household spending, birth intervals greater than 24 months, and health education on infant and young child feeding were more likely to achieve the minimal dietary diversity requirements. Conclusion The proportion of the minimum dietary diversity was higher than in previous studies from Ethiopia. The minimum dietary diversity was higher than in previous studies from Ethiopia. Family planning for birth spacing, nutritional counseling on infant and young child feeding, and parent communication in a child's feeding are critical to improve dietary diversity in a child's feeding.