Abstract Well-defined, three-dimensional (3D) flowerlike metallic Co microcrystals with several radiating hexagonal-tapered petals assembled by particles size of 150–250 nm were fabricated via a facile hydrothermal reduction route under a fixed basic condition. The morphology and structure of the products were characterized by scanning electronic microscopy (SEM), energy-dispersive X-ray (EDX), transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS) and powder X-ray diffraction (XRD). The probable formation mechanism of the flowerlike Co microcrystals was discussed based on the experimental results. Magnetic properties of Co microcrystals were investigated by a commercial Physical Properties Measurement System (PPMS). The flowerlike products exhibited ferromagnetic characteristics with a saturation magnetization of 128.1 emu/g and a coercivity of 232.5 Oe at room temperature. Compared to the coercivity value of bulk Co, the products displayed a remarkable enhanced value due to their special morphology.