A task‐specific mesoporous organic polymer (TSPOP) with unique features like good porosity and rich aromatic phenyl groups was facilely made and utilized as a promising adsorptive desulfurization absorbent for the first time. The material exhibits an efficient saturated adsorption of dibenzothiophene (DBT), as high as 111.1 mg g−1. In addition, the intrinsic mesoporous skeleton of TSPOP gave rise to a facile incorporation of uniform Ag(I) species inside the network which facilitated the uptake of organosulfur compounds. A significantly higher saturated DBT adsorption for Ag(I)‐loaded TSPOP reaches 203.7 mg g−1 via a multiple‐site interaction. A detailed model study based on the density functional calculation provides a deeper understanding of the origin of this high activity. In addition to the π–π stacking between DBT and phenyl rings, there exists an additional π‐complexation adsorption with Ag(I) ions, thus, significantly improving the DBT capture performance. © 2016 American Institute of Chemical Engineers AIChE J, 62: 1740–1746, 2016