As well as Immigration and ACC Minister, he is also the minister in charge of the Employment Relations Amendment Bill, currently before select committee.
It includes a range of measures that aim to strengthen collective bargaining, but the National Party is warning that the changes could shrink the job market.
Lees-Galloway admits his upbringing is not the usual formula for becoming a Labour minister. He grew up on a small beef farm in south east Auckland, near Waiuku, and was educated at King's College.
"My mum was true blue 'til the day she died (from bowel cancer). Socially conservative. Right-wing, economically."
How did she feel about him becoming a Labour MP?
"She wasn't impressed. It was a source of great conflict for her - pride that her son had made it to Parliament, but for the wrong party."
The family endured a lot of financial pain during the economic liberalism of the 1980s under the fourth Labour Government, which oversaw the axing of Government farming subsidies.
"We were lucky in that we didn't come from generations of farmers, so our whole family wasn't completely invested in farming. A lot of our neighbours were, and for them it was just the end of their livelihoods. People walked off their land," Lees-Galloway says.
"The change was necessary but it was too fast and too brutal, and people were left behind. If the process had started earlier, it could have been done at a pace where people were able to make the transition."
Lees-Galloway's political shape didn't begin forming until he was at Massey University in Palmerston North, where he earned a BA in English. He became active in the student union and campaigned for interest-free student loans, which the Labour-led Government picked up in 2005.
"That was a huge win for us. It made me realise that when we band together around a common cause, we can actually do a lot of good."
After he graduated, he worked in a communications role for three years for the nurses' union in Palmerston North, "minding my own business" when then-Palmerston North MP Steve Maharey retired from politics in 2008.
When Lees-Galloway won Palmerston North that year, his majority was a slim 1117. Last year, it was a comfortable 5319.
Now 38, Lees-Galloway is one of the youngest members of Cabinet in a political landscape where employment law reform will be a key battleground.
Jono Naylor, former Palmerston North Mayor and former National MP, describes Lees-Galloway as a pragmatic politician who plays the ball, not the man.
"He was always open to different ideas and was keen to do what it took to get the result, and quite realistic about what you can achieve.
"I've got confidence that he won't ignore employers. He's smart enough to realise that if he simply comes at it from a workers' rights perspective, rather than recognising the role everyone plays in the economy, then it wouldn't be enduring."
The Government's intention to bring in industry-wide Fair Pay Agreements will be a test, and Lees-Galloway says he wants to find a solution that won't simply be repealed by the next National-led Government.
The details will be worked through over the next 12 months in consultation with business groups, unions, and other stakeholders.
He has already earned some praise from Business NZ chief executive Kirk Hope, who said he was encouraged by the minister's willingness for dialogue.
"I think Business NZ is keeping its powder dry with the new Government," says National MP Michael Woodhouse, who Lees-Galloway shadowed on workplace relations, immigration and ACC while in Opposition.
Woodhouse said he and Lees-Galloway worked together in areas including zero hour contracts and harsher penalties for exploiting migrant workers.
"But then having reached an agreement, he claimed a victory he didn't deserve - but that's the politics of it."
He said his amicable private relationship with Lees-Galloway often contrasted to the public political jousting.
"Deep down, they don't want to do anything that's going to be bad for New Zealand, but I do worry that some of the things they've been saying around immigration and employment law would indeed damage us economically, culturally and socially.
"It's too soon to tell whether the willingness he says he has to consult and collaborate is backed up by actions."
National's workplace relations spokeswoman Amy Adams said Lees-Galloway had yet to reach out to her, disputing his claim that he offered to work with her on paid parental leave.
"He hasn't in any way reached out on his legislative programme to me, but even more important is that he takes time to work with businesses, and I really hope he does that."
National is warning that Fair Pay Agreements will see employers compelled to comply with minimum industry standards, even if they were not part of the negotiations.
Lees-Galloway has moved to allay fears, saying industry-wide strikes will not be allowed, and it will up to industries, not the Government, to work towards agreements.
"We are creating the tools and the framework and then intend to hand over to industry to decide what is in their best interests."
Looking forward, he is using the lessons of the 1980s and the impact the rapid changes had on his family.
"Change is necessary, but we need to make sure we make that change with people, not to them. I know what's it like to have change done to you, and for it to be pretty brutal.
"We are only going to see more of the gig economy, more contracting, more of the non-traditional type of employment relationships. We can pretend it's not happening, or we can start making adjustments now that are good for workers, but also support changes that are good for business.
"And we can make the transition at a pace that people can adjust to."
