This study examined the relationship between family income and students’ academic performance in selected public secondary schools in South-East Nigeria. A cross-sectional school-based survey design was adopted, involving 260 Senior Secondary Two (SS2) students drawn from Abia, Anambra, Ebonyi, Enugu and Imo States. Family income was classified into five monthly income categories, while academic performance was measured using students’ last-term average percentage scores and grade categories. Other variables included parental education and occupation, family type and size, supplementary tuition, adequacy of learning materials, meals per day, attendance and study hours. The data reveal a pronounced socioeconomic gradient in academic achievement: students from higher-income households generally recorded higher scores and were more strongly represented in the distinction category, while lower-income students were concentrated more heavily in the fail and pass categories. Higher family income also coincided with greater access to supplementary tuition, adequate learning materials, regular meals, longer study periods and higher attendance. The findings indicate that family income is an important socioeconomic correlate of academic performance and that differences in educational resources constitute plausible pathways through which economic inequality may be reflected in students’ outcomes. Because the design is cross-sectional, the observed relationships are interpreted as associations rather than definitive causal effects. The study recommends targeted educational support, school-based supplementary learning, improved access to learning materials, nutrition support and equity-sensitive educational policy.