The Defense University has certain educational and training standards that Cadets or Students must meet, but there are still some cadets who do not meet these standards which prevents them from being promoted to the next level. Cadet competency is a key factor in the relationship between education and training and learning achievement. The aim of this research is to analyze competency as a mediating variable that connects the influence of education and training with cadet learning achievement. This research uses quantitative methods with a causal approach. Path analysis is used to determine whether there is an influence between variables, as well as testing models between variables that have a causal form. Data was collected from 240 cadets as a sample from a population of 602 using samples selected using stratified random sampling techniques. The research results show: 1) There is a significant positive relationship between education and learning achievement. 2) There is no significant effect of training on cadet learning achievement. 3) There is a significant positive relationship between competency and cadet learning achievement. 4) There is a significant positive relationship between education and cadet competency. 5) There is a significant positive relationship between training and cadet competency. 6) There is a significant positive relationship between education and cadet learning achievement which is mediated by competency. 7) There is a significant positive relationship between training and cadet learning achievement which is mediated by competency. The conclusion is that competency has an influence on improving the learning achievement of Defense University Cadets.