The use of the laser powder bed fusion (LPBF) method, which is one of the novel production techniques, has received widespread attention. One of the significant issues using this process is the need to use pre-alloyed powders with specific properties. Using in-situ alloying enables the processing of alloys beyond those commercially available. Therefore, the development of methods such as in-situ alloying is necessary. This study used a mixture of aluminum and copper powder to prepare samples of in-situ Al-5Cu alloy through LPBF. After achieving optimum process parameters for producing dense alloy samples, considering that this alloy is heat treatable, a series of heat treatments were performed at similar temperatures to evaluate the effect of annealing as well as aging time on mechanical properties. According to the results, with increasing aging time, micro-hardness increased. On the other hand, as the solution time decreased, a micro-hardness lower than the as-built samples was achieved. Finally, the increase of microhardness up to twice that of pure aluminum showed a promising prospect of achieving improved mechanical properties in this alloy compared to pure aluminum and similar alloys. These results are highly significant considering the use of Al-Cu alloys in the production of internal combustion engine components for automobiles, and they highlight a promising outlook for the application of parts produced through this method in the automotive industry.