The market share of Islamic banking in Indonesia is still low. In Indonesia, most Islamic banks are owned by their parent conventional banks. As subsidiaries of conventional banks, the profits earned by Islamic banks are attributed to their parent conventional banks, thereby increasing the overall revenue and profitability of the parent bank. The main objective of this study is to evaluate the impact of conventional banks' majority ownership of Islamic banks on the development of the Islamic banking industry in Indonesia. The study’s objective is to encourage the government and banking regulators in Indonesia to increase the market share of Islamic banking. This research was conducted using a descriptive qualitative approach. The population is Islamic banks and parent conventional banks of Islamic banks in Indonesia, with samples of Bank Syariah Indonesia (BSI) and Bank Mandiri. The instruments used are the financial statements of the Islamic banks sampled and the financial statements of their parent conventional banks. Data analysis was conducted on BSI profit earned and the recognition of the profit earned in the financial statements of Bank Mandiri. In 2022, BSI's profit contributed 50,5% of the total contribution of all Bank Mandiri subsidiaries. This will undoubtedly impact the growth of Bank Mandiri and can increase the market share of conventional banks in Indonesia. There needs to be a policy made by the government and the regulator, namely the Financial Services Authority (OJK), that there is no majority ownership of Islamic banks by conventional banks or even the separation of Islamic banks from conventional parent banks. The government and OJK should be actively involved in formulating policies and regulations that support the separation of guidelines and rules that support this separation to increase the market share of Islamic banking in Indonesia.