Abstarct: Volunteer actions play a key and decisive role in the sustainability and effectiveness of non-governmental organizations (NGOs) and charitable activities. Understanding the factors that influence these actions can lead to improved performance and enhanced social participation. This study aims to identify and prioritize the factors affecting volunteer actions in NGOs and charitable organizations. The research is applied in nature and employs a mixed-methods approach (qualitative–quantitative). In the qualitative phase, a secondary analysis of interviews conducted in the “Simaye Nikookari” project of the Atlas of Charity in Iran was performed, and themes related to factors influencing volunteer actions were extracted. The findings indicated that the influencing factors fall into three main dimensions: governance, organizational, and socio-cultural. In the quantitative phase, the Fuzzy Analytic Hierarchy Process (FAHP) was used to validate and prioritize the dimensions and sub-criteria. The results revealed that the socio-cultural dimension, with the highest weight, is the most influential, and among the sub-criteria, education and empowerment play a prominent role. This study can serve as a scientific basis for designing targeted policies and programs to strengthen and develop volunteer actions in NGOs and charitable organizations.