The Principality of Lüneburg (later also referred to as Celle) was a territorial division of the Duchy of Brunswick-Lüneburg within the Holy Roman Empire, immediately subordinate to the emperor. It existed from 1269 until 1705 and its territory lay within the modern-day state of Lower Saxony in Germany. The Principality was named after its first capital, Lüneburg (Lunenburg), which was ruled jointly by all Brunswick-Lüneburg lines until 1637. From 1378, the seat of the Principality was in Celle. It lost its independence in 1705 when it was annexed by the Electorate of Brunswick-Lüneburg, but retained its vote in the Reichstag as Brunswick-Celle.

When the Principality of Lüneburg emerged as a result of the division of Brunswick-Lüneburg in 1269, the domain of the Lüneburg princes consisted of a large number of territorial rights in the region of Lüneburg, but it could not be described as a unified state because many rights were owned by other vassals of the imperial crown. Not until the acquisition of numerous counties and rights in the 13th and 14th centuries did the rulers of Lüneburg succeed in building a unified state. Following the division of the principalities of Brunswick-Wolfenbüttel and Lüneburg between Bernard and Henry in 1409 the territorial development of the state was largely complete. At that time, the Principality of Lüneburg included the larger part of the Lüneburg Heath and the Wendland and measured about 11,000 square kilometres (4,200 sq mi).

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