This research examines the crystallography, microstructure, and mechanical properties of AISI 904L super austenitic stainless steel (SASS) joint by laser beam welding (LBW). The results indicated that the B3 and B4 specimen’s weld metal (WM) microstructure (the minimum value at the welding heat input of 0.117 kJ/mm and the maximum value at the welding heat input of 0.200 kJ/mm) comprised almost all austenite (dendritic + interdendritic) phases. Some Cr23C6 and Cr2N precipitates appeared at the grain boundaries and in the interdendritic region due to post-weld heat treatment (PWHT). Besides, it was obtained that the dendritic structure increased due to the rise in heat input. While most of the grains in WM displayed orientation in [111] and [101], it was detected that they displayed orientation in [001] and [101] with PWHT. While the high-angle grain boundary (HAGB) ratio of the B4 specimen was found to be high, the low-angle grain boundary (LAGB) ratio of the B4H specimen was found to be also high. In addition, the KAM was reduced with the effect of PWHT. Kurdjumov-Sachs (K-S) and Nishiyama-Wasserman (NW) orientation between grains with FCC/BCC structure was observed in WMs of B4 and B4H specimens. The highest mechanical properties were mostly obtained in the specimens joined by the lowest welding heat input. Fracture surfaces of tensile and impact samples of laser welded joints showed mixed mode fractures, i.e. ductile and partially cleavage fractures.