Campbelltown signed a Sister City agreement with Koshigaya City in Japan on 11 April 1984.

What began as an agreement has developed into a more meaningful relationship. With a range of exchange programs and activities taking place over the years, the Sister City bond has evolved, giving residents of both cities a global perspective on cultural connections through the values of friendship, respect and harmony.

To commemorate the beginning of the relationship, Koshigaya Park (Campbelltown) and Campbelltown Park (Koshigaya) were both constructed in 1984. In 1989, Koshigaya City donated a tea house which is now part of the beautiful Japanese Gardens in the Campbelltown Arts Centre. In return, Campbelltown City donated a number of native birds to Koshigaya when the Campbelltown Forest of Wildbirds was officially opened in 1995.

The Campbelltown-Koshigaya Sister City relationship celebrated its 30th anniversary in 2014.