Thin-film nanocomposite (TFN) membranes prepared by embedding nanofillers into an ultrathin polyamide layer have paved the way toward developing high-performance reverse osmosis (RO) desalination membranes. Scale-up production of TFN membranes is still a challenging issue, however, since previous studies have merely followed the same fabrication method for conventional RO membranes. Herein, we introduced a novel preparation method for TFN membranes using spray-assisted nanofiller predeposition to circumvent the limitations in conventional methods. The precise control of nanofiller (ZIF-8) loading was possible by simply varying the spraying ZIF-8 concentration. Most importantly, TFN membranes prepared by both spray and conventional method showed similar RO performance, while the spray method only requires similar to 100 times the minimal amount of ZIF-8 with the most unprecedentedly short deposition time (<1 min) ever reported. Our results revealed that the spray method would be promising for the scale-up production of TFN membranes in terms of cost, time, and controllability.