Background: Financial risk protection is one of the pillars of universal health coverage. Community based health insurance (CBHI) scheme is the risk sharing mechanism to reduce large out-of-pocket payments for health care and to overcome financial barriers to access health care. However, evidence on the level of willingness to join community based health insurance in the study area was scanty. Objective: This study aimed to assess willingness to join community based health insurance scheme and its predictors among informal Sectors in Buno Bedele zone, Southwest Ethiopia, 2021. Methods: A community-based cross-sectional study design was conducted on willingness to join community based health insurance and its predictors among informal sectors in Buno Bedele Zone, South west Ethiopia from January 01 to 30, 2021. Multistage simple random sampling was used to select 555 households. Data were collected using a semi-structured intervieweradministered pretested questionnaire. Data were entered into Epi-Data version 3.1 and analyzed with SPSS Version 25. A binary logistic regression model was fitted to determine the presence of statistically significant associations between the dependent and independent variables at p-value <0.05 and AOR values with 95% CI. Finally, fitness of the model was checked by using Hosmer and Lemeshow goodness-of-fit test. Results: Of the sampled respondents, 543 participated in this study with response rate of 98.3%. Of these, 426 (78.5%) were willing to join the scheme. The study found that, educational status of who can read and write [AOR=3.96; 95% CI, 2.02, 7.75], family size > 5 [AOR=2.61; 95% CI, 1.45, 4.17], poor households [AOR=4.89; 95% CI, 2.79, 8.57], experience of an illnesses in the last three months [AOR=2.28; 95% CI, 1.21, 4.30], had information about CBHI [AOR=2.24; 95% CI, 1.18, 4.25] and participating in any indigenous community insurance [AOR=7.86; 95% CI, 4.47, 3.83] were significant predictors of willingness to join the scheme. Conclusion: The study revealed that more than three fourth of respondents were willing to join CBHI. Educational status of who can read and write, family size > 5, poor households, experience of an illnesses, had information about CBHI and participating in any indigenous community insurance were more likely to join the scheme. So, the government should strengthen efforts to scale up this scheme in the informal sectors specifically to areas not yet implemented, to reduce direct out-of-pocket payment at service delivery points. This will contribute to guarantee informal sectors access to quality health services without facing financial hardship, to achieve universal health coverage for all.