The development of nanoscale materials for optical chemical sensing applications has emerged as one of the most important research areas of interest over the past decades. Nanomaterials exhibit highly tunable size- and shape-dependent chemical and physical properties, show unique surface chemistry, thermal and electrical properties, high surface area and large pore volume per mass unit area. Because of their unique and advantageous features they can help to improve sensitivity, response time and detection limit of sensors. In this review, recently developed photoluminescence-based optical chemical nanosensors are presented. Some future trends of the nanomaterial-based optical chemical sensors are given.