This study aimed to reveal the level of cognitive beliefs and awareness of bioethical issues among biology teachers in Muscat, Al Sharqiyah South, and Al Sharqiya North governorates. The study applied a mixed method to achieve the study's aims, administering three different instruments: an epistemological beliefs questionnaire, an awareness of controversial bioethical issues questionnaire, and a semi-structural interview card. The Epistemological Beliefs Questionnaire consisted of 22 items divided into five dimensions, and the awareness of the bioethical issues questionnaire consisted of 21 items distributed over six issues. The interview card dimensions consisted of two open questions and a question composed of five positions on bioethical issues. After verifying the validity and reliability of the tools, the two questionnaires were applied to a random sample of (121) teachers. Moreover, the researcher interviewed (15) teachers of biology who were chosen intentionally. The results of the study revealed that the level of biology teachers' cognitive beliefs was low while their level of awareness of bioethical issues was at a high level. In addition, the results showed no statistically significant differences at the significance level (α ≤0.05) in epistemological beliefs and awareness levels towards bioethical issues among biology teachers due to the gender variable. The results also revealed the absence of a statistically significant correlational relationship at the significance level (α≤0.05) between the epistemological beliefs and the level of awareness of bioethical issues among biology teachers. In addition, the interview results showed the dominance of the religious principle, then the utilitarian principle, followed by the humanitarian principle, and the societal principle ranked fourth in the principles that biology teachers relied on in judging bioethical issues. Based on the results, the study recommended the importance of conducting training programs that contribute to gaining deep knowledge in the dimensions of (absolute authority, innate ability, and confirmed knowledge). It also recommended conducting more studies on the effect of employing teaching practices on bioethical issues in strengthening the epistemological beliefs of pre- and in-service biology teachers.