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The objective of the present study is to investigate the effects of nickel (Ni) on the microstructure and impact toughness of coarse-grained heat-affected zone (CGHAZ) of high-strength low-alloy steel. It was observed that the microstructure of CGHAZ predominantly consisted of bainite and a small proportion of martensite-austenite (M-A) constituents and acicular ferrite (AF). With increased Ni content, the percentage of M-A constituent decreased and AF increased; consequently, the impact toughness of CGHAZ increased. The study revealed that a small addition of nickel significantly affected the formation of M-A constituents and AF; however, no obvious influence was observed on the bainitic microstructure of high-strength low-alloy steel.