Mr Morrison said 12 boats had been turned back as part of Operation Sovereign Borders.
"The majority of that occurred it the earlier part of this calendar year," he told ABC radio.
"We ensured that when we put the turn back operations in place, that we knew we could do them safely, effectively and sustainably. Our ability to that has been the critical blow to people smugglers.”
Mr Morrison also confirmed the use of lifeboats.
“There were four orange lifeboats that were used as part of turn back operations,” he said.
“Those turn backs were to Indonesia.”
Mr Morrison said the Coalition’s immigration policies had been safe and successful, saying that 45 asylum seeker voyages had also been "disrupted" and 1600 stopped from reaching Australia.
He said there had been partnership operations with Malaysian, Indonesian and Sri Lankan authorities to stop the voyages.
Mr Morrison dismissed comments that it was "mission accomplished" on border control, but said the government was "dealing with the problem".
“The past year’s successes, I think, speak for themselves," he said.
