In today’s globalized economy, both achieving international growth and integrating sustainability (ESG) practices are key strategic issues for companies. Companies operating abroad encounter different regulatory environments and stakeholder expectations, which often encourage higher ESG (environmental, social, governance) performance as they adapt to foreign norms. Similarly, strong ESG performance can facilitate international expansion by improving a company’s reputation and reducing the risks perceived by investors and partners. The interaction between a company’s foreign presence (e.g., share of foreign revenues), size and capital structure, and ESG performance is complex and partly reciprocal. Large multinational companies in particular face intense scrutiny, while small and medium-sized enterprises (SMEs) may become international companies through green shoots or may be constrained by resource limitations. This study examines these dynamics and proposes a conceptual model that links internationalization, firm characteristics, and ESG performance, treating firm type (SME or large firm) as a moderating factor.