On the 7 January 1467 the King of Poland Kazimierz Jagiellończyk granted Cracow's castellan the prerogative of erecting a town on the River Wieprz at the mouth of the River Świnka.
The parish village's name - Łęczna was to be adopted. In the past this town was mainly famous for lavish, splendid and oriental fairs which were also well-known in remote parts and attracted a large crowd. Thousands of sellers, merchants, middlemen from Russia, Germany, Austria even distant regions of the Polish Kingdom were gathered at a fair in Łęczna. They generated large sales volume and a lot of money came into the market. The town's fairs, developed settlement, the values of its architecture (the castle, the town hall, the marketplace with ornamented facades of houses), its continual increase in population made Łęczna a significant municipal, trading and craftsman's centre which functioned on more than a local scale. The period of town's prosperity was in the renaissance time. Numerous fires (1525, 1552, 1564, 1569), plagues (1693, 1710), the enemies' attacks of Tatars (1500, 1502) and Swedes (in the 17th century) did not weaken its position. In the 19th century, due to the downfall of the Polish Republic, the three partitions of Poland, the period of struggles (against foreign attacks), periodic economic no-growth, the town's importance was declining. Ultimately in the 20th century Łęczna became one of many small agriculture and trading-oriented municipalities (in the area of Lublin voivodeship), which remained outside the mainstream of country's economic development. The 1960s brought the beginnings of change. In the town's outside area a big coalfield was discovered. It was significant for the growth of its region's industry and economic progress. In 1975 not far from the town, in Bogdanka, the construction of the first leading coal mine in The Lublin Coal Basin was undertaken and Łęczna became the capital of newly formed coal-basin. The Lublin Coal Basin was to offer new prospects to the town and the whole region. Thus Łęczna entered an advantageous phase. Today, when the time of euphoria has elapsed and the harsh reality prevented the town from accomplishing great plans. Succesfully, Łęczna no longer boasts the period of vivid growth.