An advanced accident-tolerant FeCrAl alloy, C35 M (Fe–13Cr–10Al–1Mo, at %), and its laser-fusion weldments were studied after neutron irradiation up to 1.8 dpa at 357 °C to evaluate the radiation damage and $\alpha$′-precipitation kinetics. Results show that the densities of $\alpha$′ in the fusion zone (FZ) and the heat-affected zone (HAZ) were only a third of that in the base material, i.e., 2.3 × 1024 m−3. Density of dislocation loops in the FZ and HAZ were less than half of that in base material. The size of $\alpha$′ precipitates and the dislocation loops were found to be smaller in base material, compared to FZ and HAZ. The variances in microstructural response within the different regions were attributed to initial as-welded states of each region, indicating the impact of the pre-irradiation condition on radiation response in FeCrAl alloys.