"Sharks play an important role in our marine ecosystems, and we need to ensure the appropriate management of the 113 species of shark in our waters.
"This ban builds on New Zealand's proud history of balancing conservation and the prudent use of resources to ensure their long-term sustainability."
Mr Guy put the early implementation of the ban down to "widespread support".
"I'm very pleased that the [fishing] industry has risen to that challenge, and worked with the Ministry for Primary Industries, the Department of Conservation, and other stakeholders to look at options for a more rapid implementation of the ban," he said.
It is already an offence under the Animal Welfare Act to remove the fin from a shark and return it to the sea alive. The ban will also make it illegal to catch a shark, kill it, remove its fins and dump the carcass at sea.
The ban would "effectively eliminate finning in New Zealand" without having undue impacts on fishing operations Mr Guy said.
A combination of 'fins attached' and 'weight ratio' methods will be used to implement the ban.
There will be ongoing monitoring of the ban by MPI, with a view to refining management arrangements over time if required.