•We have reported a controlled chemical method for preparing 1–5μm FeCo particles.•The large grain FeCo particles exhibit high saturation magnetization of 199–211Am2/kg.•High compaction density of 7.1–7.4g/cm3 is achieved from as-synthesized FeCo particles. A direct controlled chemical method for preparing large grain FeCo particles with micron level has been reported in this work. Nearly spherical bcc-FeCo alloy particles with average particle size of 1–5μm have been synthesized by controlled reduction reactions of Fe2+ and Co2+ ions in the water/CTAB/n-butanol/n-hexane microemulsion system. The micron-scale FeCo particles exhibit good intrinsic magnetic properties with high saturation magnetization of 199–211Am2/kg, due to their high purity and single bcc-FeCo phase. The FeCo-based magnetic cores with high density of 7.12–7.45g/cm3 can be produced via powder compacting molding process. The simple preparation process, good air stability, high saturation magnetization and good compaction ability for the chemically synthesized micro-scale FeCo particles, promise the great potential use of these materials for the full-density, near-net-shape and complex-shaped FeCo-based soft magnetic devices in high-power applications.