Artistic swimmers Kate Shortman and Izzy Thorpe qualified for Tokyo 2020 after finishing seventh at the Olympic qualification event in Barcelona.
The British duet scored 85.2230 for their technical routine and 85.7332 for their free routine for a total of 170.9562.
Austrian sisters Anna-Maria and Eirini Alexandri won the event with 182.8053.
Shortman and Thorpe achieved three personal best scores at the European Championships last month.
Team GB has been represented in artistic swimming, formerly known as synchronised swimming, at each Games since Beijing 2008.
A total of 22 teams will compete in the artistic swimming duet competition in Tokyo from 2-4 August.