The study investigated the academic success of secondary school students in Ondo State. The study employed the survey design technique. The population for the study consisted of secondary school students III in Ondo State. The sample of 500 students was selected using simple random sampling technique. Three Local Government Areas (LGAs) were selected from the three senatorial district in Ondo State using simple random sampling technique. Fifteen secondary schools were selected from the three LGAs using simple random sampling technique. Thereafter, 500 students were selected across the 15 schools using intact class of the senior secondary school students III. An adapted instrument titled “Personality Traits, Cognitive Styles and Academic Success Questionnaire” (PCAQ) containing four sections was used to collect data from the respondents. Data collected were analysed percentage, Pearson product correlation coefficient and multiple regressions. The results showed that 40.8% of the students possessed high level of academic success; 34.0% had moderate level while the remaining 25.2% of students demonstrated low level of academic success. The results showed that neuroticism with 45.4% was the prevalent trait among the students. Also, the results showed that 68.4% of the students employed field dependent cognitive style. Again, the results showed positive and significant relationship between openness (r = 0.991; p < 0.05); conscientiousness (r = 0.991; p < 0.05), extraversion (r = 0.989; p < 0.05), agreeableness (r = 0.984; p < 0.05) and neuroticism (r = 0.984; p < 0.05) and academic success of students. Further, it was showed that field dependent cognitive style had negative and significant relationship at (r = - 0.477; p < 0.05) while field independent cognitive style had positive and significant relationship (r = 0.989; p < 0.05). The results revealed that openness (t = 6.12; = 0.41); conscientiousness (t = -455; = -024), extraversion (t = 9.1; = 0.28); agreeableness (t = 1.66; = 0.047) and neuroticism (t = 1.92; = 0.055). Also, the results for cognitive styles showed that field dependent (t = - 11.03; = -.069) and field independent yielded (t = 7.12; = 0.00). While the results of openness, extraversion and neuroticism were significant at 0.05 level of confidence, values of agreeableness and conscientiousness were not significant. Also, both field dependent and field independent cognitive styles were significant at 0.05 level of confidence. It was concluded that more students demonstrated neurotic trait and few had high level of academic success.