Lumajang Regency is a regency located in the East Java province of Indonesia. It encompasses a total area of 1,790.90 square kilometers and serves as a geographical region within the eastern portion of the island.
The regency shares land borders with Jember Regency, Probolinggo Regency, and Malang Regency, while its southern coastline borders the Indian Ocean. According to census data, the population was 1,006,458 in 2010 and reached an official estimate of 1,116,231 by mid-2024.