The usage of high strength steel (HSS) is steadily increasing, primarily driven by the pursuit of weight reduction, leading to a subsequent decrease in greenhouse gas emissions. This paper investigates the impact of various post-weld heat treatment (PWHT) temperatures of 525°C, 550°C and 575°C with a holding time of 2h on both the microstructure and mechanical properties of weld metal produced using a HSS metal cored wire. The investigation reveals that PWHT does not significantly alter strength but has a more pronounced influence on toughness. The as-welded condition exhibited the highest toughness. Among the samples subjected to the PWHT, the one treated at 575°C showed the highest impact energy, reaching 69  J at −60°C. This outcome is attributed to the increased presence of acicular ferrite in the microstructure, surpassing that of samples subjected to PWHT at different temperatures.