Like other small millets, foxtail millet (Setaria italica L.) is also rich in nutrients and as a short duration crop it fits to different cropping systems . Field experiment was carried out at Eastern block farm, Agriculture college and Research Institute, TNAU, Coimbatore, Tamil Nadu during summer season to study the performance of Foxtail millet based intercropping system for improving the productivity, sustainability and economics in Western Zone of Tamil Nadu under irrigated conditions. The experiment was laid out in Randomized Block Design (RBD) with seven treatments and replicated three times. It comprised of seven treatments viz., T1 - Foxtail millet (sole crop), T2 - Foxtail millet + green gram (3:1), T3 - Foxtail millet + Vegetable cowpea (3:1), T4 - Foxtail millet + Coriander (3:1), T5 - Foxtail millet + green gram (4:1), T6 - Foxtail millet + Vegetable cowpea (4:1), T7 - Foxtail millet + Coriander (4:1). The results clearly showed that the highest grain and straw yield under intercropping system was obtained when foxtail millet was intercropped with vegetable cowpea it was closely followed by intercropping with green gram. The foxtail millet grain equivalent yield (FMGEY) was computed to be in the range of 2411 to 3873 kg ha-1. The highest values for FMGEY were obtained with vegetable cowpea at two different ratios intercropping, whereas intercropping with green gram (4:1) resulted in lowest FMGEY. Foxtail millet intercropped with vegetable cowpea at 3:1 ratio recorded highest B:C ratio of 2.59. Intercropping index like land equivalent ratio was higher in all intercropping systems except coriander (1.1) at two different ratios, relative crowding coefficient (RCC) was higher in foxtail millet + vegetable cowpea (1.0) at 3:1 ratio and competition index (CI) was higher in foxtail millet + coriander (1.09) at 4:1 ratio.