The aircraft arrived in India last week, Boeing said, after leaving Seattle, Wash.
"This marks an important milestone -- the halfway point for P-8I deliveries to India," said Dennis Swanson, Boeing Defense and Space vice president in India. "The program's success the past year is really a testament to the great work between Boeing, the Indian Navy and industry."
"The Indian Navy is putting the first three P-8Is through their paces operationally, and the P-8I delivered ... will begin flight trials in the coming months," said Leland Wight, Boeing P-8I program manager.
The P-8, which is replacing the U.S. Navy's P-3 Orion, is based on Boeing's 737 commercial aircraft. It has a maximum speed of 490 knots and a range of 1,200 nautical miles.
It is produced using an in-line assembly process, as is the 737.
Boeing said the aircraft features open system architecture and advanced sensor and display technologies.
Among Boeing's team for the P-8 program are CFM International, Northrop Grumman, Raytheon, Spirit AeroSystems, BAE Systems and GE Aviation.