In this paper, we have reported a simple and rapid approach for the large-scale synthesis of β-Co(OH)2 nanoplatelets via the microwave hydrothermal process using potassium hydroxide as mineralizer at 140°C for 3h. Calcining the β-Co(OH)2 nanoplatelets at 350°C for 2h, porous Co3O4 nanoplatelets with a 3D quasi-single-crystal framework were obtained. The process of converting the β-Co(OH)2 nanoplatelets into the Co3O4 nanoplatelets is a self-supported topotactic transformation, which is easily controlled by varying the calcining temperature. The textural characteristics of Co3O4 products have strong positive effects on their electrochemical properties as electrode materials in lithium-ion batteries. The obtained porous Co3O4 nanoplatelets exhibit a low initial irreversible loss (18.1%), ultrahigh capacity, and excellent cyclability. For example, a reversible capacity of 900mAhg−1 can be maintained after 100 cycles.