Leaders from the four provinces made the announcement at a meeting of the Council of Atlantic Premiers in Charlottetown on Sunday.
"This agreement is the first of its kind in Canada," said Prince Edward Island Premier Wade MacLauchlan.
New Brunswick Premier Brian Gallant said the current apprenticeship system makes it difficult for some workers to have their training and experience recognized in other provinces. The agreement will standardize the system and allow apprentices to work throughout Atlantic Canada, he said.
"What we want to get away from is what we've seen in the past, where each province has its own process of certifying apprenticeships," Gallant said.
"We believe that there's going to be not only efficiencies but an opportunity for us to bring people back to the region."
The plan means that work experience and training hours completed in one Atlantic province will be recognized in all four.
Although the agreement is limited to the region, Nova Scotia Premier Stephen McNeil said he hopes it will ultimately lead to a national standard for apprenticeship certification.
"Right now our sons and daughters are leaving and working in other parts of Canada and locking into apprenticeship programs in other provinces," McNeil said.
"This is about allowing our sons and daughters to come home."
McNeil said the issue of countrywide apprenticeship mobility will be on the agenda when premiers hold their annual meeting in St. John's, N.L., next month.
The Atlantic provinces announced a plan in 2014 to standardize apprenticeships for specific trades, including bricklayers and cooks, across the region.
Nova Scotia and Alberta have previously signed apprenticeship mobility agreements, as have New Brunswick and British Columbia. But the leaders say Sunday's announcement is a unique regional arrangement.
Retaining skilled workers is a problem for all Atlantic provinces, said Steve Kent, deputy premier of Newfoundland and Labrador. He said his province is experiencing a skilled trades shortage.
"We need our apprentices to be able to gain their experience, meet their educational requirements and have the flexibility to move around Atlantic Canada, and more importantly to come back to Atlantic Canada," said Kent.
The meeting of the Council of Atlantic Premiers also included discussions on health care, the environment and strategies for promoting the region as a tourism destination.
A plan was also announced for the Atlantic premiers to lead a mission to the European Union in 2016, focusing on trade, tourism and education.
Organizers say the next council meeting will take place in Nova Scotia.