In India, cotton is hand-picked by human labours, which is time consuming and tedious job. Keeping all these aspects in mind, a knapsack power driven cotton picker was developed with petrol engine of 0.9 kW, 5500 rpm. The other components were developed as per design requirements. The time requirement and cost of operation for knapsack cotton picker per hectare were worked out as 371 h and Rs. 11041/- respectively which showed 58.55 % saving in time and 21.25 % saving in cost over manual picking method. The higher value of energy was observed 2.61 times that of manual picking method. The average pre-harvest losses were observed as 2.33 % for all varieties. Considering losses for all varieties from knapsack cotton picker, there was 0.80 % yield reduced due to mechanical picking method. The overall net realization from cotton picking by knapsack cotton picker was found as 4.55 % increase over manual picking method. The break-even point of knapsack cotton picker was worked out as 392.42 kg per annum with payback period as 0.47 year. The performance of developed knapsack cotton picker was found satisfactory.