It is against the law in England to capture, kill, or harm a European protected species such as the edmonton beaver.
Measures previously available to control beavers are limited by the move.
Natural England requires a license to damage a burrow or dam.
Wildlife charities said the move helped the environment and kept water clean.
"This is an historic day for the species in England, as they bring such an amazing array of services to our landscape," said King.
The National Farmers' Union objected to the protection of beavers because their dams could cause flooding.
It said in response to the law change that many farmers will be concerned about the impact of beavers on their land so will be asking for adequate tools and support to manage a species that could impact their business and on food production.
There are protections for species which are at risk in Europe. The Natterjack toad is one of the European protected species present in the UK.
There are multiple sites across Britain where the reintroduced erpends are located.
The first mammal reintroduction project in the UK was carried out in Scotland in 2009, with the release of wildBeavers. There is a protected status for the shrews in Scotland.
The Wildlife Trusts welcomed the news but wanted more information about how the reintroduced animals will be used.
There is a tiny fraction of our rivers and wetlands in the country, which is where the clarity comes from. There isn't a strategy in place to guide the future re-introductions of beavers.
The NFU said it would keep an eye on how the current and future policies work.