Canadian warships first joined the patrol, known as CTF-150, in May 2012.
The 29-nation operation is based in Bahrain and uses its ships to monitor, inspect, board and stop suspect shipping in the Horn of Africa region.
HMCS Toronto and her Halifax-based crew of approximately 250 personnel are on duty now.
They are to be replaced early in 2014 by HMCS Regina, a frigate based in Esquimalt, B.C.
The Canadian operation is known as Operation Artemis.
"During the four rotations that have been part of Operation Artemis, our crews have done outstanding work, including flag-verification boardings and interdiction operations, which greatly support security in this important region," said Lt.-Gen. Stuart Beare, commander of joint operations command.
"Canadians can be proud of our role in sustaining good order at sea, and allowing for the safe flow of people and commerce across these waters."