The journey of the APA is 10,000 miles and will make show-the-flag stops along the way.
"We're very proud to watch APA sail off and begin her important role in providing maritime security, search and rescue and humanitarian relief," said Nigel Stewart, commercial director of BAE Systems Maritime.
"This highly capable and versatile ship performed extremely well during training with the Brazilian navy, which is a great credit to all those who designed, built and delivered her."
The Amazonas class vessels are based on the British navy's River Class Offshore Patrol Vessels. They are 295 feet in length and are armed with a 30mm cannon and two 25mm guns.
BAE delivered the first of three vessels under the $198 million contract last year. The third OPV will be delivered in June.
Under the contract with Brazil, BAE systems is providing ancillary support services and also providing a manufacturing license for future Amazonas OPVs to be built in Brazil.