In the study reported on here we examined the relationship between irrational beliefs and stress levels among orphans in public secondary schools in Kenya. Rational Emotive Behaviour Theory was adopted. In the study we adopted a cross-sectional correlation research design. A sample size of 350 double orphaned students in secondary schools was obtained using stratified and simple random sampling techniques. The Irrational Belief Inventory and Perceived Stress Scale were used to collect data. The reliability results indicate the Cronbach's alpha values ranging from 0.672 to 0.756. Quantitative data from questionnaires were analysed using inferential statistics such as Pearson correlation and regression analysis. The findings established a weak positive (n = 314, r = 0.149; p = 0.008 < 0.05) Pearson product-moment correlation coefficient between demandingness and stress levels; a weak positive (n = 314, r = 0.243; p < 0.05) correlation between awfulizing and stress levels; a weak positive (n = 314, r = 0.191; p < 0.05) correlation between irrational belief for low frustration tolerance and stress levels; and a weak positive (n = 314, r = 0.167; p = 0.003) correlation between irrational belief of worthlessness and stress levels. The implication of these findings is that orphaned students are overwhelmed with stress because of their state of irrational beliefs. It is recommended that school counsellors should train orphans in secondary schools on rational beliefs through therapy techniques such as positive self-talk to counter the irrational beliefs.