Casa Pia Atlético Clube was founded in Lisbon on 3 July 1920, growing out of football played at the Casa Pia de Lisboa charitable school, whose teams date back to the 1890s and were pioneers of the sport in Portugal. The club's home is the Estádio Pina Manique in the Belém area of Lisbon.

Casa Pia won the Lisbon Championship in its earliest seasons and took part in the inaugural Primeira Liga in 1938-39, but then spent more than eight decades outside the top flight. Promotion in 2022 ended that absence and the club has remained in the Primeira Liga since, playing home fixtures at the Estádio Municipal de Rio Maior while Pina Manique does not meet top-tier requirements.

The team plays in black and white and is nicknamed Os Gansos, the Geese.