This study assessed the efficiency of non-governmental organisations (NGOs), comparing International Non-governmental Organisations (INGOs) and Local Non-governmental Organisations (LNGOs) in Mezam Division, Cameroon, within the broader context of development effectiveness. The study examined how efficiently NGOs transformed inputs into outputs and compared performance across organisational types. A quantitative survey design was employed, using Data Envelopment Analysis (DEA) under the CCR model with Excel Solver to evaluate efficiency based on donor funding, staff capacity, and communication/technology expenditure as inputs, and beneficiaries reached and community groups supported as outputs. A sample of 226 NGOs, comprising 34 INGOs and 192 LNGOs, was analysed. The findings revealed substantial efficiency disparities among the NGOs. Only 7.5% were fully efficient, whereas 71.7% were highly inefficient. INGOs demonstrated relatively stronger performance, with 14.7% achieving full efficiency compared with 6.3% of LNGOs, reflecting differences in governance, funding stability, and managerial capacity. However, widespread inefficiencies persisted in both categories, particularly among LNGOs. The findings were consistent with international evidence supporting DEA as a useful tool for benchmarking NGO performance and highlighted local challenges related to weak governance, limited resources, and inadequate internal controls. The study recommended institutionalising DEA-based efficiency assessments, strengthening capacity building, adopting performance-based funding, and improving monitoring and evaluation systems. It further advocated national NGO efficiency benchmarking standards, stronger stakeholder collaboration, and the establishment of a Charity Board for Cameroon to enhance accountability, resource utilisation, and sustainable development outcomes.