But these days, his personal fortune is conservatively estimated at €10m, and his favoured mode of transit is his silver Porsche 911, a 1968 classic.
The Porsche is just one of four luxury cars he owns, according to a recent interview. But whether he will need to sell off some of his more-disposable assets to fund a possible future divorce remains to be seen.
Keating's surprise separation from his wife of 12 years Yvonne was described yesterday as "amicable", but his wife of 12 years would be entitled to a significant percentage of the couple's joint wealth in the event of divorce.
The couple count celebrity solicitor Gerald Kean amongst their closest friends.
The Keatings, until recently, lived together in a six-bedroom home in the exclusive Abington development in Malahide, Co Dublin.
Dubbed 'Neo-Georgian for the neo-rich', other owners of the vast, period-style mansions include Westlife's Nicky Byrne.
The Keatings paid more than €2.7m for their home in 2001, and afterwards helped to launch two showhouses in the development. At that stage, they also had a beautiful home in the K Club in Straffan, Co Kildare, which they later sold.
"We thought when we decided to buy here we might be sacrificing our privacy, but actually it's no sacrifice," Yvonne said at the launch. "Nobody really comes here and we're never bothered."
Her husband's interest in property had begun years earlier when, aged 18 and flush with the early success of Boyzone, he paid out close to €200,000 for the home he grew up in and gave it to his parents.
Some time after his mother's death, he bought another home for his father Gerry.
He also bought a property in Surrey, England, basing himself there for a time as he focused on his solo career, before selling it on, also at a profit.
It is understood that the Keatings still have property interests in Portugal -- where they have a summer home -- and the US, and were, at least until recently, developing a further property in Ireland.
However, the source of most of Keating's wealth is, of course, music.
The 33-year-old started out in Boyzone aged just 16, and for the first 10 months they made €350 per gig after expenses.
Despite being the youngest, Keating was put in charge of collecting the money by manager Louis Walsh who noticed the lead singer's interest in learning about the industry.
Keating would later be heavily involved in the early career of the Westlife boys, another lucrative sideline.
In 2005, the respected 'Sunday Times' Rich List estimated his wealth at €10m, based on the 30 million records he had sold as part of Boyzone and as a solo artist, with a total of nine number ones in the UK.
Although often criticised as being a 'covers' band, Keating wrote the majority of their original songs, which meant he earned the bulk of the royalties.
But after a promising start to his solo career -- including two number one albums in the UK -- he began to falter a little.
Nevertheless, his wealth was estimated at €15m in 2007, at the height of the property boom and around the time that negotiations on a Boyzone reunion began in earnest.
The band returned to touring again in 2008. "We had to risk £3m (€3.5m) of our own money to fund the stadium concerts, as we couldn't get backing from record companies at first," the singer said at the time.
"But we believed in ourselves -- and it was a sellout."
The money made from the subsequent tour undoubtedly helped offset the property crash that must have affected the singer's financial state, and another number one album will have helped the bottom line further.
Keating also recently signed a six-figure contract to appear as a judge on 'Australia's Got Talent'.
But the money wasn't all one way. As well as property and looking after his family, cars were always a big interest, while the singer christened his yacht 'Fair Play', a nod to his character on the 'Gift Grub' comedy show.
But nobody can doubt his keen commitment to charity either.
It is estimated his family has raised in the region of €8m for the Marie Keating Foundation following the death of his mother from breast cancer.
In a recent interview, Keating said his most valuable possession was "a limited-edition print of Steve McQueen, which I bought at a gallery in Los Angeles".
"It's one of only two in the world, and I keep it in the music studio at my house."
Source Irish Independent
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