In the present study, self-propelled cabbage/cauliflower harvester was designed, developed and evaluated. The machine consisted of different components like engine, frame, shearing (cutting) unit and power transmission unit. The power transmission unit consisted of main clutch, shearing blade operating clutch, belt drive unit, chain and sprocket drive, universal joint and cutter blade assembly. The main working principle of harvester is based on shearing of crop stem against high-speed rotating blade. The power from the engine is transmitted by belt-pulley drive unit to transmission shaft on which chain and sprocket is mounted on one side and then power is transmitted to shearing blade coupling with the help of a stationary pulley and fixed socket. Average mean head diameter of the selected cabbage and cauliflower was 89.5 ± 15.24 mm and 107.5 ± 15.24 mm, respectively. Average mean stem (plant) diameter of the selected cabbage and cauliflower was 18 ± 4.85 mm and 21.5 ± 3.08 mm, respectively. The shearing force increased with increase in diameter of stem. The optimum performance of the machine was achieved when it was operated at 1.5 km/h forward speed and the shearing blade moving at speed of 147 rpm. The mean field capacity for developed prototype was observed as 0.063 ha/h and 0.053 in case of cabbage and cauliflower, respectively with field efficiency of 91.97 and 90.48 %. The average head damage was negligible (0.15 %) for both the crops. The average untrimmed percentage with developed harvester was 3.2 and 3.0% in case of cabbage and cauliflower crop, respectively. The developed machine helps to increase the field capacity in cabbage/cauliflower harvesting due to 7-times more capacity and 50% cheaper compared to traditional method of cabbage/cauliflower harvesting. At the operating condition of forward speed (1.5 km/h) and shearing blade speed (147 rpm), the machine could harvest 0.5 ha of cabbage and 0.42 ha of cauliflower farm per day of 8-h. This same task would have required between 15 labour per day if entirely done manually.