In the developing world, projects in the communities play a very important role in sustainable socio-economic development. It is therefore important for such communally based project to be planned and designed in such a way that they benefit communities sustainably, over a long period. In Kenya, incidences of projects’ failure to serve the intended communities are rife. Many projects stall soon after commissioning. There are various explanations for projects’ unsustainability, amongst which entail non-inclusion of key parameters of project development in project management. This study was carried out in counties in Western Kenya. It analyzed collaboration as a key factor in the sustainability of community based public health projects. Funding was considered as a moderating criterion. The study adopted descriptive survey design. A sample of 360 respondents was purposely sampled from of a population of 5570 committee members of projects in public health facilities. Data was sourced through question-naires, interview schedules, and document analysis and observation checklists. The computations for correlation on the influence of stakeholder participation on sustainability was at valuer = 0.895, with a coefficient of determination at 0.801. This translates to 80.1%, of change in project sustainability attributable of collaboration. ANOVA obtained was at R value o.888, implies 80.1 % of change in sustainability was attributable to collaboration. Further, the rate of change, computed at Y= 0.888X+c (constant), implied positive change, at rate of 0.888 between the two variables. Therefore, collaboration as a key criterion in sustainability of public health projects. Consequently, the study recommends that for public health projects to sustainably serve the communities, players must encompass the aforesaid criteria in project design, planning and management. These findings should therefore inform and empower all players on the great value realized by incorporating collaboration in project management.