Arroio Grande is a Brazilian municipality in the southern part of the state of Rio Grande do Sul. It covers an area of 2,513.60 km² (970.51 sq mi) and has a population of 18,238.
Agriculture was the primary industry until the 1970s and is now the municipality's second industry. The population is predominantly urban, with about 80% of residents living in urban areas and 20% in rural areas.
Much of the municipality's area consists of plains.