Two-dimensional (2D) magnetic semiconductors with room-temperature ferromagnetism are very desirable. Despite the great progress made recently, the Curie temperature is still very low (similar to 45 K), originating from the weak ferromagnetic superexchange interaction. Here, based on first-principles calculations, we propose a general route to achieve 2D magnetic semiconductors with enhanced Curie temperature in organometallic frameworks by incorporating antiaromatic rings as organic linkers. Antiaromatic rings usually possess low-energy multiple spin states, which can be easily induced by adjacent magnetic moments of transition metals and subsequently coupled with them through the strong d-p direct exchange interaction, producing high-temperature ferrimagnetic ordering. The design of 2D organometallic frameworks with typical antiaromatic rings such as pentalene, which show Curie temperatures well above room temperature from classic Heisenberg model Monte Carlo simulations, confirms our proposal.