The synchronisation of nutrient release with crop demand is a key advantage of controlled-release fertilisers (CRFs), offering potential benefits for sustainable hill rice production. However, conventional CRFs often use non-biodegradable polymer coatings, raising environmental concerns. This study evaluated the performance of an eco-friendly CRF, Greencoat (NPK 15:4:18), formulated using biodegradable cellulose polymers derived from jackfruit waste and corn cobs. A two-season field experiment was conducted in Bau, Sarawak, to assess the effects of six fertiliser treatments on yield performance and nutrient (N, P, K) uptake of hill rice. The control (T1) followed the government-subsidised SBRPB package, while T2–T6 involved single applications of Greencoat at sowing (0 DAE) at rates of 100–500 kg/ha. Significant inter-seasonal differences were observed in yield and yield components, with Greencoat at 200 kg/ha (T3) consistently recording higher yields than the control, achieving 2.62 t/ha and 1.65 t/ha in the first and second seasons, respectively, which represented 8.6 to 18.0% yield improvement. Nutrient uptake patterns at panicle initiation and maturity stages showed no significant differences between T1 and T3, indicating sustained nutrient availability from a single Greencoat application over the 150-day growth cycle. These results demonstrate that Greencoat CRF can serve as a sustainable, biodegradable alternative to conventional fertilisation for hill rice systems, reducing labour input and environmental impact without compromising yield performance.