The church will submit the petition to Parliament in October. The government decided to revive the death penalty in 2013 but has yet to implement it.
Following national and international outcry, the prime minister Peter O’Neill-led government has indicated it is reviewing its decision.
Public support for dropping the death penalty continues to mobilise, with 19 Catholic dioceses across the country working on the petition.
Port Moresby Archbishop John Ribat said the death penalty is not an answer to deter serious crimes.
“So when the Parliament sits again in October we will be able to present this petition.
“It is the government’s prerogative to make it a law and if the government doesn’t listen, at least we have voiced our concerns, as believers and as Christians.
“Then if the government does listen to our petition and does repeal the law against the death penalty to the advantage of the people, then we would say that we have been blessed.”