Purpose In Indonesia, subjective issues towards the fundamental of Islamic banks (IBs) have been arising. For example, they are claimed to be not in line with the Shari‘ah (Islamic law). Furthermore, the existing scholarly works have not much gained knowledge from the local IBs explaining their efforts in promoting maqasid al-Shariah (objectives of Islamic law). Hence, because religiosity drives the fundamental establishment of IBs, this paper aims to explore the knowledge of how IBs in Indonesia promote maqasid al-Shariah via their published reports. Design/methodology/approach This paper performs text mining from 24 official reports of 5 IBs in Indonesia published from 2015 to 2017. The sample contains 7,162 digital pages and approximately 3,021,618 words. Traditional text mining via human intelligence is first performed to analyse for the numerical data required in the maqasid al-Shariah index (MSI) analysis. Furthermore, a computer-driven text mining using the ‘Text Search’ feature of NVivo 12 Plus is conducted to perform qualitative analysis. These approaches are made to gain relevant knowledge of how the sampled IBs promote maqasid al-Shariah from their published reports. Findings The analysis using the MSI explains a quantified maqasid al-Shariah on the sample’s performance, which indictes the lowest and the highest performing banks. Furthermore, a qualitative analysis supports the evidence from the quantitative analysis. It explains the authors’ coding process that results in 2 parent nodes and 20 child nodes, which contain 435 references coded from the sampled unstructured and bilingual texts. These nodes explain the information that associates with maqasid al-Shariah from the IBs’ reports. These findings explain how maqasid al-Shariah is measured mathematically and represent relevant knowledge of how maqasid al-Shariah is informed practically via digital texts. Research limitations/implications A positivist generalisation is neither intended nor established in this study. Practical implications This paper gains relevant knowledge of how the sampled IBs in Indonesia control and maintain the implementation of maqasid al-Shariah from large textual data. Such knowledge is practically important for IBs stakeholders in Indonesia; moreover to help navigate the Shari‘ah identity of Bank Syariah Indonesia (BSI), the new IB established from the merger of 3 state-owned IBs, which are among the sample of this study. Social implications This paper provides evidence that might best challenge the subjective issue of IBs claiming that they are not in line with the Shari‘ah, particularly in Indonesia. Originality/value This paper is among the pioneers that discover knowledge of how IBs promote maqasid al-Shariah in Indonesia’s banking sector via a text mining approach.