Microstructure gradient is formed during the additive manufacturing of Ni-based superalloy Haynes® 282® via electron-beam melting powder-bed fusion (EB-PBF) process. The precipitation of secondary phases occurs owing to EB-PBF in-situ heat treatment as consequence of high temperature powder bed pre-heating and multiple melting and re-heating thermal cycles, which can be summarised as a carbide precipitation heat treatment at 1000–1025 °C/8 h, aging between 875 and 975 °C/30 h, followed by a slow cooling step. Relatively large precipitates formed inter- and intragranularly with M3B2 boride and gamma-prime (γ') have sizes of approximately 5 μm and 110 nm, respectively, at the bottom of the build. The size of the precipitates decreases along the build direction. In the top region, the precipitate sizes of boride and γ' are 1 μm and 50 nm, respectively. MC carbide with a size of <1 μm precipitated throughout the build. A good correlation is observed in terms of the γ' size to hardness with average values of 350 HV at the bottom and 400 HV at the top. The ultimate tensile strength (UTS), yield strength (YS), and elongation (EL.) values at the bottom and top regions are 1080 ± 40 MPa, 805 ± 25 MPa, and 20 ± 5%; and 1105 ± 20 MPa, 825 ± 15 MPa, and 25 ± 5%, respectively. Overall, EB-PBF Haynes® 282® exhibits higher UTS and YS but lower EL than those of the as-received wrought alloy (950 ± MPa, 650 ± 15 MPa, and 40 ± 5%, respectively).