Purpose The purpose of this paper is to report the possible impact of intellectual capital (IC) on firm reputation (FR) and investigates if there is a relationship between FR and market internationalization (MI). Design/methodology/approach The data were collected from engineering consultancy firms (ECFs) in Turkey. The study employed structural equation modeling to examine the hypothesized relationships between IC, FR, and MI of ECFs. Findings ECFs with strong human and structural capital can have a good FR. However, healthy relational capital may not lead to the same effect on FR. On the contrary, FR can create high-quality relational capital for ECFs. Lastly, a good FR, based on robust human and structural capital, can provide the success of ECFs' MI process.,Social implications ECFs that can be active in the international arena may maintain their services by financial sustainability. Thus, the advantage may result in a prosperous society. Originality/value The study is first to suggest a model joining IC and FR for the MI process of ECFs. This is suitable for competition of ECFs that are willing to be sustainable firms.