This study implemented intervention strategies to enhance grade 12 students' mathematics perception and self-efficacy to improve their mathematics achievement. Conveniently selected 394 students (200 as comparison & 194 as treatment group) were involved. Two FGDs were conducted. Forty items of mathematics achievement test were administered for both groups. Next, interventional training focusing on mathematics perception and self-efficacy enhancement strategy (innovative classroom-based) was given to the treatment groups. Counseling psychologist and mathematics teachers participated in the training that took 12 class-periods within 3 weeks. Math test, perception, and self-efficacy given before were given for the second time for both groups at the end of the training. Quantitative data were double-entered into SPSS version 26, cleaned, and analyzed using descriptive and inferential statistical techniques. Qualitative data were transcribed, coded using Atlas Ti7 software, and analyzed in the form of narration. The finding of this study revealed a statistically significant mean difference in students' mathematics perception [t (392) = -5.28, p < 0.001], self-efficacy [t (392) = -3.40, p < 0.001], and mathematics achievement [t (392) = -6.45, p < 0.001] between comparison and treatment groups. The effect size result of both of students' mathematics perception and self-efficacy revealed a small effect (r = 0.257 & 0.169), respectively, whereas mathematics achievement revealed a moderate effect (r = 0.309). Interventional training was given to adjust students' mathematics perception [t (193) = -3.64, p < 0.001], and self-efficacy [t (193) = -14.98, p < 0.001] was effective. There was no statistically significant difference between male and female students in their mathematics achievement post-test result, i.e. [t (192) = 0.45, p = 0.66].