The aim of this study is to predict the problem-solving skills of high school students according to irrational beliefs and decision making styles. The sample group of study consisted of 223 (150 girls and 73 boys) voluntary high school students in Istanbul. Problem Solving Inventory, Melbourne Decision Making Scale, Irrational Beliefs Scale-Adolescent Form and Personal Information Form were used as data collection tools in the study. After the data was entered with SPSS 22 package, Multiple Linear Regression and Pearson Korelation analysis was applied in the study. According to the findings, the problem-solving showed negative correlations with irrational beliefs, panic decision-making style, delaying decision-making style, shy-away decision-making style; positive correlations with careful decision-making style. Irrational beliefs and decision-making styles accounted for the 85% of the variance for the problem solving. But the deceptive decision-making style and the shy-away decision-making style are not significant predictors of problem solving alone. The findings were discussed in the light of relevant literature and suggestions were presented.