This study focuses on the tensile strength properties and microstructural development of A588 Grade K high strength low alloy (HSLA) steel. The research involves welding of 4 mm thick HSLA using E308L filler wire in the MIG welding process. The correlation between microstructure and tensile strength is explored with a welding current ranging from 120–150 A and a welding speed between 2–6 mm/s, rest of the parameters are consider as a constant. Results indicate that, the combination of 130 A and 2 mm/s reveals the better mechanical properties, exhibiting enhanced tensile strength with fewer defects compared to other parameters. Notably, the improved tensile strength at 130 A is 1.07 times higher and at 120 A is 1.05 times higher than that of the friction stir welding (FSW) process. However, there is a noteworthy improvement compared to laser welding, with 1.034 times at 130 A and 1.06 % at 120 A. The microstructure evolution in various zones are studied, no major defects are found, and confirming a transformation of ferrite morphology in the heat affected zone (HAZ), particularly with an increased amount of acicular ferrite in the fusion zone under the 130 A input current. The paper further details the tensile behavior and fracture morphology analysis under the specified experimental conditions.