In this paper, we consider a roughly convex multiobjective optimization problem and use the concept of the outer \(\gamma \) -convexity (resp., the \(\gamma \) -convexlikeness) of the objective mapping, where \(\gamma >0\) is the roughness degree of the objective one, to show that every \(\gamma \) -local weak efficient solution (resp., \(\gamma \) -local efficient solution) of the considered problem is also a global weak efficient one (resp., global efficient one). Necessary and sufficient conditions for efficiency solutions are established by using \(\gamma \) -subdifferentials. Examples are also given to illustrate the obtained results.