Foundational Literacy and Numeracy (FLN) has become a central priority of primary education in India under the National Education Policy (NEP) 2020 and the NIPUN Bharat Mission. Policy implementation, however, depends on how teachers interpret curriculum expectations, select pedagogical strategies, assess learning, respond to learner diversity, and adapt their practice. This paper is presented as a conceptual paper supported by a critical review of policy documents, large-scale learning assessments, and selected empirical studies relevant to teacher competencies and FLN in India. It synthesises evidence from the Foundational Learning Study (FLS), Annual Status of Education Report (ASER), PARAKH Rashtriya Sarvekshan, teacher-focused FLN studies, and literature on teacher knowledge and professional learning. The review indicates that teacher competence is multidimensional, encompassing content knowledge, pedagogical knowledge, assessment literacy, inclusive practice, communication, digital competence, and reflective professional practice. The paper proposes a revised Teacher Competency–FLN Achievement Framework (TCFAF) in which teacher competencies are linked to FLN through classroom processes and learner engagement, while professional development and structural conditions operate as enabling or moderating factors. The framework is not presented as evidence of a causal relationship; rather, it offers propositions that can be tested empirically. The paper concludes with implications for teacher education, continuous professional development, school leadership, and future research.