The objective of this study was to analyse the relationship between pre-service teachers’ (PSTs’) discursive algebraic skills and their written mathematical (specifically algebraic) achievements. The conceptual design consists of three theoretical perspectives that are merged in the study. This study used a mixed-methods design, combining quantitative and qualitative approaches. The PSTs completed an algebraic knowledge test designed to identify their discursive and algebraic knowledge, and a content analysis of their written texts was then performed. The written texts focused on algebraic patterns, concepts and their generalisation related to rational numbers, patterns in multiplication tables, proportionality and combinatorial concepts, including permutations and combinations. The results of this study are not generalisable due to objective limitations and the contextualisation of the research within a specific learning environment. However, the findings confirm the theoretical perspectives proposed by Vygotsky, Freudenthal and Kriegler’s theoretical framework, and support the view that the development of prospective teachers’ writing ability is not an isolated learning process. Rather, it likely occurs through interaction with the acquisition and development of algebraic content knowledge. Future research should include more empirical and analytical studies on the development of PSTs’ discursive algebraic knowledge, particularly the processes underlying the formation and growth of proficiency in mathematical writing.