A solvent free strategy for the mechanochemical synthesis of 3-acylchromones has been developed via FeCl3-nanocellulose mediated dehydrative coupling of ortho-hydroxyarylenaminones and carboxylic acids. The ortho-hydroxyarylenaminones undergo electrophilic domino cyclization followed by an unusual acylation event with carboxylic acids in the presence of FeCl3 as the catalyst and nanocellulose as the reaction media. The protocol was found to be simple, efficient, and environmentally benign to obtain a diverse array of 3-acylchromones with high yields. The protocol features advantages such as the use of cheap and readily available carboxylic acids as acyl source and no requirement of directing groups, oxidants, and solvents. Furthermore, the utilization of a wood-derived material, nanocellulose as the biodegradable reaction media and nontoxic iron salt as the catalyst under very mild and solvent-free conditions makes this acylation protocol very interesting in the perspective of the Green Chemistry principles.