This article discusses the institutional conformance of Halal Certification Organisation (HCO) to the development of Halal Tourism Industry (HTI). It seeks to understand how the HCO, which provides Halal certification for wideranging products in the tourism industry, performs the institutional adjustment towards changes in its surrounding environment. In so doing, this article utilises institutional theory and instrumental qualitative case study approach to examine two notable HCOs in Indonesia and Thailand, namely Majelis Ulama Indonesia (MUI) and the Central Islamic Committee of Thailand (CICOT) based on Global Muslim Travel Index (GMTI). Despite the unchanging organisational forms and structures, the two HCOs have been developing innovative functions and measures to adapt the institutional pressure of HTI. Adapting to the rapid development of HTI, the two HCOs provided Halal certificate for Muslim consumers' protection, increased export of goods to a number of Muslim countries, and provided Halal tourism services to augment the competitiveness of respective Halal tourism destination. © 2018 Institute for Tourism.