Stakeholder participation is increasingly becoming important in achieving high project implementation performance. However, there is limitation of studies on how stakeholder participation approach is being implemented towards Ethiopian development projects such as agricultural transformative projects. This study therefore intends to assess the effect of stakeholder participation at all stages of a project lifecycle (PLC) on the performance of Ethiopian agricultural projects considering ATA ACC program as a case. The study employed mixed research method. Quantitative data was collected through survey questionnaires applied to 250 staffs of implementing organization, focal persons of long-term government owners and representatives of donor agencies participating in 19 projects under ACC program, using census. A semi-structured interview was utilized to gather qualitative data from 5 high profile personnel of the three organizations. Accordingly, a response rate of 76.8% was obtained for the questionnaire, while 100% was obtained for the interviews. Descriptive statistics and Linear Regression were used to determine the level and importance of stakeholder participation, as well as the relationship and influence of stakeholder participation on performance. The qualitative data was examined using thematic content analysis, and the quantitative data was analyzed using SPSS V.26. The findings revealed that participation in all stages of a PLC, including initiation, planning, execution, and monitoring and evaluation has a significant effect on project performance by improving sense of ownership, stakeholder empowerment, project acceptability, and leadership accountability. Finally, the study concludes by providing recommendations to organizations undertaking similar projects that are looking to improve project performance.