Overload derived from the wide use of multiple information and communication technologies (ICTs) has become increasingly pervasive. Nevertheless, our understanding of the nature of ICT-mediated overload and how such overload affects individual productivity in multi-ICT context is limited. This study classifies ICT-mediated overload into congruent and incongruent types based on content relevance. Drawing upon transactional theory of stress, we then develop a holistic model to examine their impacts on individuals’ productivity through cognitive appraisals and coping responses. Results of our empirical study of 439 respondents with ICT usage experience illustrate that congruent information overload can lead to challenge appraisal, which in turn facilitates individuals’ innovative and routine uses of ICTs, ultimately improving their productivity; incongruent information overload and incongruent interruption overload induce hindrance appraisal, which further results in avoidant ICT use, thereby impairing productivity. This study contributes to the research on overload in the context of multiple ICTs by advancing our understanding of the nature of different types of ICT-mediated overload and by uncovering the mechanisms that govern the impacts of ICT-mediated overload on individuals’ productivity.