The private sector is a key development partner, thus, its participation in government development planning and budgeting processes is crucial. This study investigated private sector participation in planning and budgeting processes in local government authorities in Makete and Njombe District Councils in Njombe Region. The specific objectives of the study were to examine spaces for private sector participation, and establish factors influencing private sector participation in LGAs’ development planning and budgeting processes. The study involved 40 purposively selected private sector organizations’ officials and 15 LGAs officials. Data were collected through structured interviews, key informant interviews and documentary reviews. The descriptive analysis technique was used for data analysis. Qualitative data were analysed for qualitative content analysis. The study found that the main spaces for private sector participation in LGA’s planning and budgeting processes were the submission of annual plans and budgets to LGAs, attending LGAs’ annual planning and budgeting meetings, and inviting LGAs officials to attend private sector planning and budgeting processes. The main factors influencing the private sector’s participation in LGAs planning and budgeting processes were: the policies of the private organisations, the need for transparency and accountability, the need for government support, the organization’s scope of operation and fora for lobbying and advocacy. It was concluded that the existing mechanisms were generally ‘closed’ or ‘invited’ spaces, which offered limited participation space for the private sector. Thus, there is a need for the government to widen participation spaces for the public sector, including by putting in place clear modalities for involving the private sector in LGA’s development planning and budgeting processes.