Official Thai history gives the iconic role of King Chulalongkorn as the civiliser of which is the theme underpinning my study. This thesis aims to complicate this narrative by investigating the historical specificity of Chulalongkorn's visual representation operating with the mechanisms of westernisation. The study discusses how the King presented and represented his royal person and his regal power and how the King consequently changed and shaped Siam's visual and material culture at the turn of the century. Chulalongkorn's royal family portraits and grand architectural programme, as well as his European art collection recreated a new concept of Siamese kingship and the monarchy: this wide-ranging analysis traces the shift from a semidivine to a secular and modernised monarchy. This thesis argues that the westernisation programme was a process and product of transcultural exchange within the colonial encounters between Siam, the West and their colonies. Chulalongkorn's appropriation, adaptation and reinterpretation of Western art doubly transformed the monarchy and its kingdom into a modernising nation under the pressure of Western colonialism. This compelled Siam to become a crypto-colonial state of nation. Chulalongkorn's aspiration for westernised visual representation turned political loyalty into religious devotion in later years. Collective memory of Chulalongkorn was strongly embedded in the public's perception through the practice of remembrance, nostalgia and commemoration fed by the royalist narrative in official Thai history. This thesis also contributes to an ongoing dialogue on the relations between the monarchy, memory and national identity through an investigation of celebratory exhibitions of the Chakri Dynasty. The issues of visual representation and its impact addressed in this thesis are arguably as bound up with issues of national identity and national politics.