The Australian Curriculum that forms the basis of the content taught to pre-service teachers is organised into discrete school subject areas. Concepts in STEAM subjects (such as Science, Mathematics, Technology and/or the Arts) are often taught in isolation with little cross-curricular links. It can be argued that mathematics teaching within its silo of the existing curricula in Australia is the approach to emulate, as this is how many pre-service teachers may teach mathematics in a school setting. However, it is also possible to incorporate learning experiences in each of the STEAM subject areas that recognise how each area is relevant and related to the others. This could lead to a more integrated approach (de Araujo et al., 2013) that reflects the real life contexts within which these skills are used. In order to prepare for this integrated approach, pre-service teachers will need to have a sound understanding of all STEAM subject areas. This includes viewing mathematics as more than computations and of use outside of the classroom. For this to occur, pre-service teachers will need to have a level of competency in mathematics. This study focused on pre-service Early Childhood and Primary teachers (n = 673) and their competency in mathematics. Mixed levels of mathematical competency were identified for the participants. These results are concerning as those participants with lower levels of competency may have mathematical skills and understandings that are incompatible with integrating mathematics with other STEAM subject areas in an authentic way. The development of pre-service teachers’ mathematical competency to include wider conceptions and applications of mathematics beyond the curriculum requirements appears to be crucial in successful integrated STEAM education. The opportunity to focus on integrated STEAM education and incorporate context are elements that are seen as essential in 21st century education (Organisation for Economic Co-operation and Development [OECD], 2013).