Upland rice has diverse agro-ecological attributes that can tolerate changes brought by climate change. Hence, this study aimed to determine the performance of upland rice cultivars under rainfed lowland conditions, assess the root growth of upland rice cultivars under rainfed lowland conditions, and evaluate the profitability of growing upland rice cultivars under rainfed lowland ecosystems. This was laid out in a Randomized Complete Block Design (RCBD) with three replications. Twelve rice cultivars were designated as treatments, however, only seven rice cultivars survived namely; Caimpas, Black rice, Red rice, Speaker, NSIC Rc192, PSB Rc18, and NSIC Rc27 that showed significant differences on agronomic characteristics, root and shoot parameters, yield, yield components, and harvest index. The five drought-tolerant upland rice cultivars such as Perya, Remolites, Kalinayan Monos, Tukoran, and Lebolebo showed permanent wilting due to non-adjustment of said cultivars to changes in growing conditions from sufficient irrigation water during early growth to low soil moisture and absence of precipitation during the reproductive growth phase. Improved upland rice variety NSIC Rc27 performed excellently under limited soil moisture through early heading and maturity, and high grain yield as mainly contributed by its heavier straw yield, an abundant number of productive tillers, higher filled spikelets, the heavier weight of seeds, high harvest index and adjustment of aforesaid cultivar to drought. Thus generated the highest gross margin of 1,823.16.00 USD. Therefore, it is recommended to grow NSIC Rc27 under rainfed lowland ecosystems even if this cultivar is experiencing limitations on soil moisture conditions.