Amorphous Co_70.3Fe_4.7Si₁₀B₁₅ powders were produced by a two-stage quenching technique consisting of high-pressure gas atomization followed by centrifugal spinning. The amorphous powders have a flaky morphology with a disk or an ellipsoidal shape. The thickness is as small as 1 to 3 μm and the dimension along the longitudinal direction is 25 to 300 μm leading to large aspect ratios of about 20 to 300. The composite consisting of the flaky amorphous powders embedded in phenol resin exhibits significantly anisotropic magnetic properties because of a well developed arrangement of the flaky powders along the direction perpendicular to the hot-pressing direction. Judging from the combined characteristics of the unique powder morphology and the magnetic properties inherent to the Co-based amorphous phase, the flaky amorphous powders are concluded to have a further enhanced engineering potentiality.