Sussex Day is the county day for the historic county of Sussex in southern England and is celebrated on 16 June each year to celebrate the rich heritage and culture of the county

The event takes place on St Richard's Day, the feast day of St Richard of Chichester, Sussex's patron saint. The date marks the anniversary of the translation of St Richard's body from its original burial place in the nave of Chichester Cathedral to an elaborate shrine at the cathedral on 16 June 1276.

The idea of Sussex Day came from Worthing resident Ian Steedman who in 2006 suggested the idea to politician Henry Smith, at the time leader of West Sussex County Council. Smith liked the idea and West Sussex County Council officially recognised the day in 2007.