The idea was described by former Prime Minister John Key at the time as "barking mad" because of the large fiscal cost.
TOP estimated the total cost of its policy package was $3.3 billion a year. It would be paid for by replacing New Zealand Super, which is worth between $15,000 and $20,000 a year, with the basic income of around $10,000 a year.
Over-65s would be able to top up their basic income by up to $7500 if they had earned less than $50,000 a year.
All benefits including the basic income would be linked to inflation - a shift from the current situation under which super is linked to wages. TOP said this would free up funding to expand the UBI more broadly over time.
The UBI for families with children under three would replace paid parental leave payments and the parental tax credit.
"All the work on poverty ... tells us the most potent weapon to combat child deprivation is cash," the party said in its policy document.
"It is not the only weapon but it is head and shoulders above the rest in terms of impact per dollar spent."
The new policy package also includes measures to make housing more secure, including proposals to protect life-long renters who have been locked out of the housing market by rising prices.
In a proposal modelled on Germany's laws, a landlord would only be able to evict a tenant if the property was damaged or rent was not paid, and all rentals would need to pass a Warrant of Fitness.
The party would also expand the supply of social and affordable housing provided by non-government organisations.
'THRIVING FAMILIES' POLICY
• Basic income of $200/week for every family with children under 3
• Extra $72/week for low-income families with children aged 17 and under
• Replace NZ Super with basic income of $200/week, plus an extra $7500 a year for those earning less than $50k
• Give tenants long-term security by restricting conditions for eviction
• Expand supply of social and affordable housing provided by NGOs
• Free full-time early childhood education (already announced)
• Free full-time childcare for low income parents with children aged one to three