The purpose of the study is to examine the effect of environmental insecurity on students’ academic achievement in mathematics among senior secondary school students in Zamfara North Senatorial Zone, Nigeria. The population of the study comprises all the senior secondary school students in Zamfara North Senatorial Zone, which is 22,797. From the population, a sample of 150 students was randomly selected for the study from the entire senior secondary schools in the study. Three objectives, three research questions, and corresponding hypotheses guided the study. The reliability of the instrument was determined using the Kuder-Richardson formula (KR21), and the coefficient was found to be 0.87. The major instrument used for data collection was a structured questionnaire with items on a 4-point Likert scale, which was validated by three experts. The data collected was analysed using SPSS. Descriptive statistics were used to answer research questions, and chi-square statistics were adopted in testing the hypotheses. The findings of the study show that environmental insecurity has negatively affected the students’ academic achievements in mathematics, especially for students from rural areas in the zone. It was recommended that government and non-government organizations provide a new security strategy to schools in the area to reduce its effects on the mathematical academic achievements of students.