It also owns the Got Talent, Idol, and X-Factor formats, as well as Project Runway, Family Feud and more.
If Sidewalk Karaoke is optioned overseas, the deal could mean megabucks for creator Mackey and his fast-growing firm.
In between scheduling a Skype conference call with colleagues in Los Angeles, London and Spain, Mackey seems nonplussed.
"We have done all right out of the Fremantle deal, but it is the potential that is the exciting bit," he says, shrugging. "If we can go right around the world, that will be when it all might become life-changing for us."
FremantleMedia's executive president of global acquisitions and development, Vasha Wallace, believes the Kiwi programme is "exactly what we know broadcasters are looking for".
Mackey looks at it another way.
"Selling a show like Sidewalk Karaoke is no different from selling a Subway franchise," he says. "People who want to sell sandwiches will be attracted to buying a Subway outlet because it is a recognised and successful brand.
"It's much the same with Sidewalk Karaoke. The formula has proved a hit in New Zealand so there is a good chance people will like it elsewhere.
"It is not the Kiwi way to pump up your own tyres but when you are dealing with the Americans you have to learn how to sell yourself properly and not be shy about it, either."
It is a long and winding road from Mackey's upbringing as the son of a "humble, low-key" shearer at Rangitukia, near Gisborne, to the heady world of TV production and international deal-making.
But the 39-year-old dad-of-five insists the rough and tumble of the East Coast shearing sheds were the perfect training ground for a career in broadcasting.
"The sheds is where I would hear all the great yarns, the mischief, the humour and the intrigue," he says.
"My dad would work 12-hour shifts then we would party afterwards into the wee small hours.
"We spoke a different language and lived by our own rules. You had to be quick on your feet with your tongue to survive. There was a bit of an, 'if you are not at lunch, you are lunch' vibe going on.
"All this stood me in good stead for a job in television."
As a youngster, Mackey was a keen on sport and represented Ngati Porou East Coast at rugby.
But as a schoolboy he dreamed of working in broadcasting, his ambitions fuelled by listening to a transistor radio at night in bed.
"It amazed me I could be under the blankets and be listening to people talking on radio stations in Auckland or the west coast of America," he says. "That was the first time broadcasting influenced me.
"When I was a teenager I got myself a job at Radio Ngati Porou in Ruatoria and it all kicked off from there."
Mackey left school with no qualifications but got his first real break when he hitched to Auckland for a job interview as a reporter on Te Karere.
"It was all a bit farcical, really," he says. "I was wearing a suit I borrowed from my cousin. I got changed into it in the carpark outside TVNZ but I didn't know everyone was watching me from a window."
He was "rough around the edges", Mackey says, but that job taught him much about storytelling amid the tight production demands of television.
After shifting to TV3, Mackey spent three years mostly on sports shows, including as a presenter on TV3's Best Damn Sports Show.
"I was great at getting a Maori angle on things and the sports editor eventually kept asking if I could perhaps give the cousins a rest and try to get some Pakeha into my stories," he says, laughing.
Mackey went on to become head of sport at Maori TV and created award-winning sports show Code. He founded company Black Inc Media in 2008 and after the firm was bought by Eyeworks, he became company director alongside Kiwi reality TV queen Julie Christie.
From Christie, he learned the skills to make programmes that could appeal overseas.
"Working with Julie was an eye-opener," he says. "That is where I started to get the tools for making primetime programming and discover how the commercial side of the business works.
"I was learning from the master. It was like the ultimate apprenticeship. Yes, Julie can be a task master but she is fantastic at what she does and I'm not sure we will see someone of her capabilities as a producer in New Zealand again."
Christie believes Mackey's charisma is one of his main selling points.
"He has this remarkable everyman ability to relate to all sorts of people," she says.
"And he literally knows, or is related to, everyone from politicians to All Blacks.
"His main strength is his personality and tenacity and he was always a great pitcher of shows.
"He's like a guy with three brains - the one in his head, the one in his heart and the one in his gut - and that's what you need to make it in TV production internationally.
"But he needs someone very strong to look after the money and if he wants to make it really big then he'll have to leave New Zealand."
Mackey has been executive producer of a range of shows on local television networks, including Qantas award-winner One Land and The Life and Times of Temuera Morrison.
In 2012 he found himself at the centre of a controversy with the headline-grabbing debut of The GC.
The publicly funded show was about good-looking young Maori making money, partying and chasing their dreams on the Gold Coast.
It was a ratings hit but copped flak for under-delivering on cultural content. "None of the GC crew were obese, committing crimes or unemployed," Mackey says.
"The storm about it was taxing emotionally and personally but it was simply a show about a contemporary Maori subculture. It was another learning curve."
Since he started Pango Productions with business partner Jonathon Ulrich, things have gone from strength to strength.
The company makes shows including weekly Maori current affairs offering Marae and satirical semi-topical news programme Brown Eye, with co-producer Taika Waititi. The firm has just sold its cooking series The Game Chef to the National Geographic channel.
But it is the development of a business software package for TV production companies that could be the real money-spinner, Mackey says.
"This could underpin a half-trillion-dollar global-content business and we already have clients in the United States, Australia and New Zealand. It has certainly got me out of bed in the mornings with increased vigour."
TV production rival Phil Smith, boss of Great Southern Television, describes Mackey as "the new kid on the block".
"Bailey has certainly made a splash," Smith says. "For me he is the most natural salesman in our industry. When we are at events overseas he runs his operation like a well-oiled shearing gang. He is still young and has a lot of potential."
Despite his growing success here and abroad, the mercurial Mackey insists he wants to retire at 45.
He and his partner, Kiriana, who is the financial controller at Pango, have just had a daughter.
"I have always had a never-say-die attitude but I am serious about getting out of this business early," he says. "I have worked seven days a week for as long as I can remember and I want to enjoy seeing my family growing up.
"People tell me I could never retire as I wouldn't know what to do with myself. They are wrong about that. I want to be living somewhere where there is no cellphone, no email and no hassle. I will be absolutely awesome at doing absolutely nothing."
- Herald On Sunday