The importance of addressing the topic of sustainable development has been widely acknowledged, and the researchers call for future studies that would develop new perspectives on integrating sustainability in the business context. Currently, most of such studies focus on large companies, whereas it has been shown that the impact of SMEs on the economy, the society and the environment is also significant. The present work aims at exploring the integration of corporate social responsibility (CSR) and corporate sustainability (CS) in small and medium-sized enterprises (SMEs) in the Nordic countries. Adopting a qualitative dominant mixed research method, the following objectives are achieved: using content analysis, we analyse the activities disclosed by SMEs and describe their type and focus. Further, the multiple case study of 13 SMEs operating in Sweden, Finland, Norway, Denmark and Iceland allows exploration of the process of CSR integration in companies in more detail. Using the abductive approach to analysis and systematically combining the existing approaches to analysing CSR integration with the empirical findings, we are able to distinguish several specifics of SMEs. Namely, the process of CSR integration in SMEs may be different due to increased role of the top management commitment and the varying degree of externally formalising CSR and CS through obtaining certifications. This allows us to design suggestions for the updated model of CSR integration, which would reflect these specifics of SMEs. The present work contributes to current research by exploring CSR and CS integration in the context of SMEs, which have been previously identified as research gaps. We develop suggestions for modifying an existing framework for analysing CSR integration that combines the focus on specific business operations and the stages that a company can undergo in implementing CSR. The developed model could be used as a practical tool for analysing the company and the potential areas that would lead to CSR integration on a more strategic level. The qualitative nature of the present work and supporting the theoretical reflections with quotes from SME managers and owners provides opportunities for naturalistic generalisations and gaining insights on what activities could be implemented in companies. We acknowledge that our work has several limitations. The qualitative nature of the study does not allow statistical generalisation; thus, further research is recommended to enhance the findings and test the developed model in different context and using different methods, as well as targeting not only managers and owners whose responsibilities are related to strategy and sustainability, but also employees from other functions. Quantitative and qualitative studies of SMEs in the analysed region conducted by native speakers are also recommended.