Deterioration of students' mathematics achievement has been a common problem while their mathematics perception and self-efficacy have been reported to determine their achievement. However, little is known about the potential relationships among them. Therefore, this study attempted to investigate the extent of influence of students' mathematics perception and self-efficacy toward mathematics achievement. Randomly selected 643 students for questionnaire, six mathematics teachers for interview and two FGDs were conducted with students. The findings revealed that students' mathematics perception and self-efficacy were positively and strongly related to their mathematics achievement (r = 0.767, p < 0.001 and r = 0.797, p < 0.001) respectively. Regression result reported 75.4% of the variation in students' mathematics achievement was accounted for by students' mathematics perception and self-efficacy (R[superscript 2] = 75.4). The two predictors explained a statistically significant amount of variance in mathematics achievement, [F (2637) = 975.99, p = 0.001]. Mathematics perception [[beta] = 0.44, t (17.56), p = 0.001] and self-efficacy [[beta] = 0.52, t (637) = 20.84, p = 0.001] were reported as significant predictors of students' mathematics achievement. There was a statistically significant gender difference in students' mathematics perception [t (641) = 2.77, p < 0.001], self-efficacy [t (638) = 5.43, p < 0.001], and mathematics achievement [t (638) = 5.43, p < 0.001].