Transformative assessment is a classroom assessment aimed at changing both how teachers teach and students learn a lesson. Nowadays, this kind of assessment needs to be practiced to encourage teachers to be creative and flexible when designing their assessments and for students to be reflective and take responsibility for their learning. Hence, this qualitative study aimed to examine mathematics teachers' practices of transformative assessment and the associated challenges. Data collected from eight teachers using semi-structured interviews and lesson observations were analysed thematically. It was found that teachers did, in fact, not provide evidence of practicing transformative assessment in their teaching. There was an attempt to align assessment to learning outcomes even though the assessment practice utilized remained traditional. Teachers' assessment practices focused on fast-learners while leaving behind the majority, lacking balance and equity. Teacher, student, and school-related factors were the main challenges facing the teachers during assessment practices. The study presents possible strategies by which transformative assessment practices in mathematics teaching can be developed, implemented, and sustained to improve students' learning.