Field experiments were conducted during 2017-18 and 2018-19 at Bardhaman, West Bengal India to assess the feasibility of potato (Solanum tuberosum L.) –onion (Allium cepa L.) cropping sequence under lower Gangetic plains of West Bengal. The experiment was laid out in a split plot design with six treatment combinations viz. 3 dates of sowing (D1-10 days before optimum i.e.,15th Nov; D2-optimum, i.e.,25th Nov. and D3-10 days after optimum, i.e.,5th Dec.) in main plots and two dates of harvesting (H1-80 and H2-90 days after planting), each replicated four times; immediately after harvesting of potato crop onion seedlings were transplanted. It was revealed that the potato variety Kufri Jyoti planted at optimum date (25th November) recorded the highest tuber yield (28.15 t ha-1). The results also revealed that dates of planting in potato, dates of harvesting in potato and interaction of these two factors significantly influenced the yield of onion bulbs grown as a subsequent crop in the rotation. Highest onion bulb yield (24.88 t ha-1) of variety N53 were recorded with planting of potato 10 days after optimum (5th December) and harvesting it at 90 days after planting (DAP). The highest system productivity (57.73 t ha-1) in potato - transplanted onion sequence and system net return (Rs. 371047.50) were recorded with the treatment planting potato 10 days after optimum date (5th December) and harvesting it at 90 DAP.