An indole-based microporous organic polymer (PINK) has been obtained by the condensation polymerization of 1,3,5-tris-(4-fluorobenzoyl)benzene with 3,3′-diindolylmethane via a catalyst-free nucleophilic substitution reaction. Due to the local dipole–π interactions between indole and carbon dioxide (CO₂), the uptake capacity for CO₂ reaches up to 16.0 wt% (1.0 bar, 273 K), and the high (CO₂/N₂ = 15, CO₂/CH₄ = 32) selectivities of the polymer make it a promising material for potential application in gas separation. Furthermore, the hydrogen storage is up to 2.48 wt% (1.0 bar, 77 K). In comparison to the reported porous organic polymers, the preparative strategy exhibits cost-effective advantages, which are essential for scale-up preparation. Its good performance for H₂ storage and CO₂ separation suggests that PINK with a large specific surface area shows potential use in clean energy applications and the environmental field.