Mathematics anxiety is a prevalent concern among K-12 students, with well-documented negative impacts on their academic performance, motivation, and psychological well-being. While prior research has revealed that teacher- and classroom-related factors can significantly contribute to students' mathematics anxiety, the evidence remains fragmented and inconsistent. Given the mixed findings, a systematic literature review is necessary to clarify how teacher- and classroom-level variables influence students' mathematics anxiety. Following PRISMA guidelines, the review employed a structured literature search process and predefined inclusion criteria and identified 56 relevant empirical studies. Through thematic analysis of the selected studies, four domains that captured the primary pathways through which teacher- and classroom-level factors influence K-12 students' mathematics anxiety emerged: (1) instructional strategies (e.g., gamification, cognitive activation, dialog-based activities), (2) teacher support (e.g., autonomy support, motivational style, teacher-student rapport), (3) classroom structure (e.g., clarity of classroom routine, task difficulty, and workload management), and (4) teacher characteristics (e.g., mathematics anxiety, self-efficacy, professional knowledge). Evidence indicates that cognitively engaging instruction (e.g., gamification, cognitive activation) and emotionally supportive teacher-student interactions can reduce mathematics anxiety. Further comparative studies suggest that instructional strategies enhancing students' mathematical understanding are more effective than interventions focused solely on emotional regulation. Moreover, the impact of these interventions varies across student groups, with stronger effects documented among female students, those from lower socioeconomic backgrounds, and students in rural areas. Teachers' own mathematics anxiety and low self-efficacy are consistently associated with higher levels of student mathematics anxiety. Several longitudinal studies further reveal that these effects intensify as students progress through grade levels, influencing not only their anxiety but also their mathematics performance over time. Drawing on Control-Value Theory and Social Cognitive Theory, this review highlights the mechanisms through which teacher- and classroom-related variables shape students' emotional experiences in mathematics learning and outlines implications for theory-driven, school-based intervention design.