The National Capital Commission has voted to include the mayors of Ottawa and Gatineau in all board meetings but on a non-voting basis, on the recommendation of Canadian Heritage Minister Mélanie Joly.
The decision will allow the NCC to "further deepen" its relationship with municipal partners, board chairman Russell Mills said in a news release.
"We believe this decision will foster a strategic regional alignment in building Canada's Capital as a dynamic and inspiring source of pride for all Canadians," he said in a statement.
Ottawa Mayor Jim Watson and Gatineau Mayor Maxime Pedneaud-Jobin applauded Joly's recommendation last week.
The mayors have been frustrated in the past by the NCC's approach to making decisions, which often have ramifications for the two cities, and have pushed for municipal representation on the Crown corporation's board.
Watson said taking part in NCC board discussions will allow the two cities to voice their concerns and points of view, but will also allow the mayors to report back to their own councils about the NCC's perspective.
"They're not always right, we're not always wrong, and vice versa," Watson told reporters Tuesday.
'They're not always right, we're not always wrong, and vice versa.' - Ottawa Mayor Jim Watson
"I very much appreciate Mélanie Joly. She made a commitment to deal with this quickly, and she did."
Joly said in an NCC news release Monday she was "delighted" at the decision, and promised to ensure indigenous Canadians are also represented on the board.
"Our government is committed to raising the bar in terms of openness and transparency, and these decisions are part of an effort to serve the public interest," she said in a statement.
Though the mayors have been invited to join NCC board meetings, they will be excluded during certain items, "including solicitor-client privilege, human resource or privacy matters, and the official residences of Canada," the NCC said.
The mayors will also have to abide by the same confidentiality provisions, conflict of interest rules and code of conduct as other board members, the NCC said.
The NCC added it will discuss the decision with Watson and Pedneaud-Jobin "as soon as possible" and a signing ceremony is expected "in the coming weeks."
More measures to "enhance the openness and transparency of the NCC" will be considered "in the coming months," the NCC said.