It cost him $360,000 in total, and he rented it out for $496 a week.
A year later he bought an older, three-bedroom home for $319,000 also in Picton, which he renovated and rented out for $453 a week.
But then, the ambitious tradie hit a stumbling block — the banks wouldn't lend him more money, because he had cross-collateralised, which meant he had used more than one property as security for a loan.
"I had a two-year gap where I stopped investing during that time, because I made a big mistake," he said.
"But in those two years I sought a full team of brokers and other people to help me invest in more property.
"My broker had 21 properties and he mentored me from then on and uncrossed my loans so I was able to start purchasing again."
By 2014, he was back on his feet, and Mr Walsh invested in a three-bedroom house in Brisbane, which cost $273,000, followed by another four-bedroom house in Brisbane which set him back $321,000.
In 2015 he bought his third Brisbane property for $327,000 and a house on Adelaide's fringe for $192,000.
In 2016 he bought a three-bedroom house in Carrum Downs, Melbourne for $364,000 which he has subdivided into a separate block, and he has just bought another home in Melbourne, which will settle next month.
The latest addition brings his portfolio up to nine properties, worth a staggering $4 million.
He has tenants in every property, earning $163,000 in rent each year, and his debt is around $2.3 million, bringing his net worth to $1.68 million.
Mr Walsh, now 27, and his wife Sophie, 23, rent a home in southwest Sydney and are planning to move to the city's northern beaches in the near future.
But the couple aren't content to rest on their laurels — Mr Walsh's goal is to own 20 properties and retire before his 40th birthday at the latest.
Mr Walsh, who also used to work as a train driver, has also established his own investment buyer's agency, Your Property Your Wealth, to help other Australians build their property portfolios
He said he loved passing his knowledge on to clients, especially younger people who have given up on the dream of home ownership.
"For me the biggest thing is helping other people so I probably won't retire fully because I want to continue helping others invest in property," he said.
"But it's nice to know I won't have to go back to driving trains or do something I don't want to do."
Mr Walsh said he had no other investments besides property, but that he had diversified his portfolio to cover a variety of states and regions to minimise risk.
He said one of the main messages he wanted to get out to Millennials was that they should consider "rentvesting" — renting where they want to live, and buying in cheaper, high-growth areas.
"I've done it all on an average wage and I've built a large portfolio at quite a young age — all the time I hear people saying buying is unaffordable, but there are affordable properties all around Australia," he said.
"It's about putting your money to work."
