In the administration and development of the Malaysian nation-state, each prime minister has contributed and exhibited his distinct leadership style. Abdul Razak Hussein and Mahathir Mohamad’s contributions and leadership, especially in the nation-state’s development and modernisation, are well-recognised by Malaysians. They referred to Razak as the Development Father while Mahathir is known as the Father of Modernisation. Their leaderships’ effectiveness is also evident in their outstanding achievements based on the policies and actions during their tenure as the nation’s leaders. Therefore, this study aims to discuss the achievement-oriented aspects of Razak-Mahathir leadership in Malaysia’s nation-state development. A qualitative historical descriptive design was used as the research methodology where the primary source of this study was the texts of the two prime ministers’ speeches. These sources are qualitatively analysed to explore the qualities of leadership they practised to develop and modernise the country. The results showed that leadership qualities such as stimulating people’s intellectual capacity, motivating people, good planning, demonstrating influence, emphasising togetherness, emphasising good values, exhibiting firmness, demonstrating self-confidence, being considerate, envisioning the future and acknowledging people’s contribution were practised by Razak and Mahathir in conducting their duties as prime ministers. It showed that a country can achieve remarkable development and modernisation when it is led by leaders who incorporate the aforementioned leadership qualities. This study’s social implications are as follows: first, underlining the importance of achievement-oriented leadership that can inspire the people and the government to foster a steady national development and secondly, implying the essential roles of leaders in defining and shaping a suitable nation-state concept that should be adopted in a nation-state. This study innovatively introduces a leadership model framework based on Razak-Mahathir’s achievements during their administration. It gives an overview of their successful leadership styles in governing the country, which can be applied or practised by leaders or related parties with similar roles, aspirations and goals.