The energy consumption for hydrogen production via electrocatalytic water splitting primarily originates from the oxygen evolution reaction(OER). Developing efficient and cost-effective OER electrocatalysts to accelerate the OER reaction in water electrolysis holds significant scientific and practical importance. Cobalt-based catalysts, known for their high intrinsic activity, good electrochemical stability, and high electron conductivity, have shown the capability to effectively promote the OER reaction, gradually emerging as a research hotspot in the field of chemistry and materials. Summarizing the current frontier advances in cobalt-based OER catalysts is of crucial reference value for researchers investigating electrocatalytic water splitting. This paper summarizes the latest synthesis strategies of six types of cobalt-based OER catalysts, including cobalt oxides, cobalt hydroxides, cobalt sulfides, cobalt phosphides, cobalt nitrides and cobalt selenides, reported so far for use in the field of water electrolysis, and their applicability in different acid-base environments. From a perspective more likely to replace commercial IrO₂ and RuO₂, a comprehensive discussion on different methods to enhance the external and internal activities of cobalt-based catalysts is provided, along with proposed future directions for the research of cobalt-based OER catalysts in water electrolysis.