Early diagnosis of malaria and treatment seeking behavior play key role in controlling and preventing further complication related to malaria disease. Aim of this study was to determine the responses on early malaria diagnosis and treatment seeking behavior among outpatient clients attending at Sekou toure regional referral hospital in Mwanza, Tanzania. Methods: A cross-sectional study was conducted among outpatient client at Sekou-Touré regional referral hospital, convenient simple random sampling used and self-administered questionnaire were used to collect data and data was entered into Microsoft excel and then exported to SPSS version 25.0 for further analysis and presented on the percentages and table. The analysis of strength of relationships between categorical variables was conducted using the Chi-square test. A p-value of ≤ 0.05 was considered to be statistically significant. Results: A total of 192 respondents completed the study with a response rate of 97.6%. The study revealed that Most of the respondents about 90.6% stated they would seek treatment from health facility when symptoms appear. However, only 6.3% seek treatment within 24 hours of onset of illness (p= 0.017). Half of respondents (50.5%) experienced malaria symptoms in the past six months and only 30% seek for treatment at health facility. Preference of health facility, (51%) respondents were going direct to pharmacy to buy medicine for self-treatment. Overall, cost of service, time consumed and distance of health facility especially health center shows significant with such delay. Conclusion: A low proportion of malaria-suspected patients sought treatment within 24 h of fever onset compared to the national target. Distance from the health facility, cost of service and time consumed were found to be predictors of early treatment-seeking behavior for malaria. Strengthening strategies tailored to increasing awareness for communities about malaria, importance of going hospital and early treatment-seeking behavior is essential.