Speaking at Toronto's historic Fort York, the minister said Wednesday that there are many qualified candidates to replace the outgoing chief of defence staff Walter Natynczyk.
"What I can tell you is that the process is nearing completion," MacKay said during an event to commemorate the 200th anniversary of the War of 1812.
"It will be a cabinet decision and discussion that will occur before any announcement," he said.
The Canadian Forces have a lot of leaders who have the potential to fill that role ... and the selection process is "a laborious" one, he said.
Natynczyk, whose departure is expected within weeks, has held the position for four years.
Critics say there is no obvious choice for his job.
At the end of June, a number of candidates were interviewed for the position including, namely, the current vice-chief of defence staff, Vice-Admiral Bruce Donaldson; the country's top officer at NORAD, Lt.-Gen. Tom Lawson; and the head of the Royal Canadian Navy, Vice-Admiral Paul Maddison.
Some reports have suggested the Harper government is willing to go outside the ranks of Canadian Forces brass in order to recall a trusted, retired officer to fill the position, like former lieutenant-general Andrew Leslie, who oversaw the Canadian army until 2010.
Leslie also headed a report last year that called for an overhaul of the Canadian Forces, which would result in $1-billion in savings and the re-allocation of up to 11,000 jobs.
The PMO has denied that Leslie, who is a top executive for the information technology giant CGI Group, has been interviewed.
MacKay was at the historic military site Wednesday to bestow a battle honour for regiments who fought in the Battle of Detroit.
The announcement was part of a series of events this year related to the 200th anniversary of the War of 1812.