She told the Weekend Herald she expected the trend to continue after Article 50 was triggered.
"It will be interesting to watch."
McMahon said the Irish diaspora of between 50m and 80m people was "a very big part of Ireland's story".
"Generally speaking Ireland has been including to its diaspora."
The thriving Irish economy and the nation's Rugby World Cup bid could also be drawcards for Kiwis of Irish descent to return to the motherland, McMahon said.
"The country is cracking along very well."
Meanwhile here in Aotearoa, there are quite a few Brits interested in Kiwi citizenship post-Brexit.
According to data sourced from the Department of Internal Affairs, 4906 people born in the UK were granted New Zealand citizenship in 2016 - 23 per cent more than in 2015 when just under 4000 UK citizens officially became Kiwis.
Citizenship applications from Americans also jumped after the election of President Donald Trump.
In the 12 weeks after Trump was declared leader of the free world on November 8, 170 US citizens applied for a grant of New Zealand citizenship, compared to 100 during the same period in 2015.
In total Internal Affairs approved 577 applications for New Zealand citizenship from Americans last year, the highest number in at least seven years. In 2015 only 465 US immigrants became New Zealand citizens.
And immigration officials are bracing themselves for the possibility of even more Brits and Americans flocking to our shores.
Website traffic from the UK to Immigration New Zealand's New Zealand Now website, which provides wannabe Kiwis with information about working and living here, had increased 24 per cent year on year.
People living in the UK went to the website 443,413 times in the eight months since Brexit was set in motion, with 25,741 Britons registering their interest in working, studying or investing in New Zealand.
During the same period in 2015, only 358,671 visits to the site came from the UK.
The site received an even greater influx of traffic from the US in the wake of the 2016 Presidential election.
Between November 2016 and February this year 467,494 Americans browsed the New Zealand Now website. In the same four months the previous year only 180,078 visits were logged from the US.
The number of Americans who enquired about working, studying or investing in New Zealand trebled year on year, shooting up from 7726 in the period ending February 2016 to 31,124 between November 2016 and February 2017.
Immigration New Zealand's national manager Greg Forsythe said the data "clearly shows high levels of interest in New Zealand around the time of Brexit and the American election, and ongoing interest".
The figures
• 1874 Kiwis got Irish passports in 2016, up from 1604 in 2015
• 4906 British citizens were granted NZ citizenship last year, an increase of 23 per cent from 2015
• 577 applications for NZ citizenship from Americans were approved last year - the highest number in seven years
• 443,413 Britons visited the New Zealand Now website since the Brexit referendum
• 467,494 Americans browsed the site in the four months after Trump was elected
• 31,124 Americans contacted Immigration New Zealand between November 2016 and February 2017 about working, studying or investing here. Only 7726 people from the US enquired about working, studying or investing in NZ in 2015
• 25,741 UK residents registered interest in working, studying or investing in NZ in. Only 22,245 Britons did the same the previous year.
