In this paper, a series of coumarin derivatives were synthesized, through the Pechmann condensation reaction using basalt fiber functionalized with 7‐aminonaphthalene‐1,3‐disulfonic acid (BF@(CH2)3‐Cl‐ANDSA) as environmentally friendly and heterogeneous catalyst. The structure of the catalyst was identified by FT‐IR, XRD, EDS‐Mapp, FE‐SEM, and TGA analysis. The catalyst was found to be efficient for the synthesis of coumarin derivatives through Pechmann condensation. phenols were treated with β‐ketoesters to give coumarin derivatives, under green conditions. The current method has several advantages, such as non‐toxic, short reaction time, high thermal stability, recyclability, and reusability of the catalyst.