An integrated computational materials engineering (ICME)-based workflow was adopted for the study of microstructure and property evolution at the heat-affected zone (HAZ) of gas metal arc-welded DP980 steel. The macroscale simulation of the welding process was performed with finite element method (FEM) implemented in Simufact Welding® software and was experimentally validated. The time–temperature profile at HAZ obtained from FEM simulation was physically simulated using Gleeble 3800® thermo-mechanical simulator with a dilatometer attachment. The resulting phase transformations and microstructure were studied experimentally. The austenite-to-ferrite and austenite-to-bainite transformations during cooling at HAZ were simulated using the Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation implemented in JMatPro® software and with phase-field modeling implemented in Micress® software. The phase fractions and the phase transformation kinetics simulated by phase-field method agreed well with experiments. A single scaling factor introduced in JMatPro® software minimized the deviation between calculations and experiments. Asymptotic homogenization implemented in Homat® software was used to calculate the effective macroscale thermo-elastic properties from the phase-field simulated microstructure. FEM-based virtual uniaxial tensile test with Abaqus® software was used to calculate the effective macroscale flow curves from the phase-field simulated microstructure. The flow curve from virtual test simulation showed good agreement with the flow curve obtained with tensile test in Gleeble®. An ICME-based vertical integration workflow in two stages is proposed. With this ICME workflow, effective properties at the macroscale could be obtained by taking microstructure morphology and orientation into consideration. © 2020, The Minerals, Metals & Materials Society.