Repurposed materials in early childhood mathematics refer to manipulatives made from recyclable or reusable items that, in this study, were co-created by children in the classroom with teacher facilitation to support developmentally appropriate, hands-on numeracy learning. This study investigates the pedagogical value of integrating student-generated repurposed manipulatives into kindergarten mathematics instruction in a government school in the United Arab Emirates (UAE). Using a mixed-method design, the research examined growth in key emergent numeracy competencies, verbal counting, one-to-one correspondence, number identification, numeral comparison, and number combinations among children aged 4–5. Participants included 62 KG-1 and 70 KG-2 students and 12 mathematics teachers. Quantitative evidence was generated through pre- and post-assessments to determine learning gains following implementation. To capture the affective and behavioural dimensions of learning, attitude measures were triangulated with classroom observations and analysis of student artefacts produced during learning-centre activities. Teachers’ perceptions of feasibility, instructional impact, and sustainability alignment were explored through interviews. The findings indicate statistically significant improvements in children’s emerging mathematical performance, alongside increased engagement, creativity, and problem-solving behaviours during interactive tasks. Teachers perceived the approach as strengthening mathematical participation while meaningfully advancing sustainability practices within early years settings. This study contributes evidence that child-authored, repurposed learning resources can function as both a numeracy intervention and a sustainability-oriented pedagogy, with implications for scalable professional development for teachers supporting high-quality implementation in early childhood classrooms.