Weed infestation is one of the limiting factors in the production of chilli (Capsicum annuum L.). Weeds reduce the availability of nutrients and water for the main crop reducing the fruit yield. The application of herbicides is not an environmentally friendly method. Therefore, there is a movement to use alternative methods for weed management. Polythene mulches have many benefits such as soil temperature modification, soil conservation by preventing runoff, nutrient addition, and improvement in soil structure in addition to minimizing weed infestation. Therefore polythene mulches are a popular method to reduce weed infestation in various crops. UV treated silver on black polythene mulch is one such polythene mulch introduced to the Sri Lankan market recently. Therefore, this research was conducted with the objectives to study the effect of UV treated silver on black polythene mulch on growth and yield parameters and weed infestation of chilli. The possibility of the reduction of the amount of recommended fertilizer with the application of UV treated silver on black polythene soil cover was also tested. The experiment was laid out in a Randomized Complete Block design with four replications. Two local chilli varieties (MI2 and MI3) popular among farmers were used for the study. The four treatments comprised UV treated polythene mulch with different percentages of the recommended fertilizer dosage (100%, 75%, and 50%) for chilli. Recommended fertilizer mixture without polythene mulch was the control treatment. Yield and weed parameters such as time taken to 50% of flowering, time taken to first picking, fruiting span, and yield per plant, number of weeds per unit area and fresh weight of weeds per unit area were evaluated. Plants in the treatments with UV treated polythene mulch exhibited a significantly higher growth and yield in both chilli varieties along with a significantly lower weed infestation. The plants grown with 100% and 75% fertilizer levels with polythene mulch did not show a significant difference in total yield, indicating the possibility of reducing 25% of recommended fertilizers. Therefore, the UV treated biodegradable silver on black polythene mulch can be recommended to obtain high production with less fertilizer and zero levels of herbicides.