Metacognition encompasses knowledge and regulation that, through reflection, sustain problem solving behaviour. How metacognitive awareness is constructed from reflection on metacognitive knowledge and regulation and how these reflections enable metacognitive skills for Mathematics problem solving remain unclear. Three secondary schools representing instrumental case studies are collectively reported here. In the quantitative part, a Mathematics word problem and a reflection questionnaire were administered to all Grade 8 and 9 learners (n = 609). From each school, a top achiever in Mathematics was invited to an individual interview in the qualitative part (n = 3) and was video recorded while solving a Mathematics word problem. The findings suggest that metacognitive reflection is embedded in the regulatory process and fosters metacognitive awareness. Metacognitive reflection constructs person, task and strategy awareness, particularly through planning and monitoring as it assembles the metacognitive skills necessary for Mathematics problem solving.