AbstractCrowdfunding based financing, via the internet, can be a solution for sustainable development. In order to better understand this under researched area, the objective of this study was to build and test a theoretical model to help understand crowdfunder behavior related to sustainable development applying the theories of planned behavior, constraints, and attachment style. To accomplish the research goals, an Internet survey was conducted between March 11 and 23, 2020 in South Korea. Data from 487 respondents, who participated in sustainability crowdfunding during the past year, were analyzed utilizing partial least squares‐structural equation modeling and multigroup analysis. Results revealed that perceived constraints related to sustainability crowdfunding had significantly negative impacts on attitude and behavioral intentions. In addition, perceptions of crowdfunding for sustainability were found to positively influence attitudes and subjective norms. Moreover, behavioral intentions were found to significantly and positively be affected by attitudes, subjective norms, and perceived behavioral control. Additionally, respondents with high anxiety attachment were found to have their perceived constraints and attitudes to have greater impacts on their behavioral intentions than their counterparts. Also, crowdfunders with high avoidance attachment were found to have larger effects between their perceived constraints and attitudes, perceived constraints and behavioral intentions, perceptions and attitudes, and perceived behavioral control and behavioral intentions than their counterparts. Accordingly, results suggest theoretical and managerial insights related to crowdfunding for sustainable development.