Consanguineous marriages are common in Saudi Arabia, increasing the risk of genetic blood disorders in offspring. This pilot study assessed the knowledge and perceived threats regarding genetic blood disorders, norms, and premarital screening for consanguineous marriage among unmarried university students in Saudi Arabia as a predictor of marriage decisions. A cross-sectional study was conducted from 22 January through 22 April 2022. In total, 400 unmarried students at Saudi Arabian universities were recruited using the non-probability convenience sampling technique. The data were analyzed using descriptive statistics and multinomial logistic regression. The results showed that the majority of participants had poor knowledge of genetic blood disorders. Most of the participants had a favorable attitude toward consanguineous marriage, while perceived threats towards genetic blood disorders were perceived as neutral by the participants. Moreover, their norms regarding consanguineous marriage also showed neutral results. A multinomial regression shows that participants with poor attitudes were significantly 22.3 times more likely to have poor marriage decisions (95% CI: 4.9–101.7,p< 0.001). However, participants with good and neutral norms regarding consanguinity marriage were significantly protective factors against poor marriage decisions with an RRR ratio of 0.165 (95% CI:0.030–0.918,p= 0.04) and 0.238 (95% CI: 0.071–0.797,p= 0.02), respectively. To mitigate the risk of genetic blood disorders in future generations, there is a need for targeted awareness campaigns about genetic blood disorders and the risks of consanguineous marriages by integrating this education into university curricula, and premarital counseling. It is also important to address societal norms, promoting informed decision-making, and provide premarital consultation to couples who carry the same mutated genes and are at risk of transmitting the disease to their offspring. Furthermore, there is a need for further research to assess the effectiveness of campaigns in this regard.