Mobilising under-utilised low carbon (ULC) land for future agricultural expansion helps minimising further carbon stock loss. This study examined the regency cases in Kalimantan, a carbon loss hotspot, to understand the key factors for mobilising ULC land via narrative interviews with a range of land-use actors and complementary desktop analyses. The factors were broadly categorised into economic, agro-ecological, institutional and cultural factors, which were perceived as opportunities and/or barriers by different land-uses and stakeholders (with different business models), and can vary across regencies. Generally, oil palm was regarded by most interviewees as an economic opportunity, reflecting that there were no other more attractive options. However, oil palm may also be limited by various factors. For example, labour availability may greatly limit the actual amount of land that can be mobilised in many regencies due to low population density. These economic factors were interlinked with the agro-ecological factors, such as soil quality, which was often regarded as the reason of low economic attractiveness. The other two categories, institutional and cultural factors, are more subtle and complex, involving socio-political elements across the hierarchy of authorities. Understanding these factors requires understanding the relationships between different stakeholders and their histories. Past analyses on ULC land largely focus on a single crop or end-use. This study shows that mobilisation of ULC land has to depart from analysing the specific conditions within individual regencies, especially considering the views of multiple land-use actors on different land-use options and business models. Future research is recommended to assess available land-use options and business models by investigating how they are affected by each of the factors identified here and accounting for the policy targets set by individual regencies (e.g. economic development or food security) and the preference and capability of local actors.