The aircraft landed at Aldergrove, near Belfast, this afternoon and then began airlifting fodder and provisions to the Glens of Antrim where thousands of livestock are feared to have died.
Temperatures are due to remain low across the course of the week with some further snow expected.
The MoD agreed to a request by Secretary of State Theresa Villiers for the helicopter because of the growing plight facing farmers struggling to trace missing sheep who have vanished in snow drifts of up to 20 feet high.
A senior official with the Department of Agriculture will be on board the Chinook to identify areas worst affected by the snow and freezing temperatures. Farmers said the conditions, especially in the Glens, are the worst in living memory.
Police and mountain rescue teams are already heavily involved in operations to reach isolated farms.
Meanwhile police have warned hill walkers of snow hazards which are "not normally seen in Northern Ireland such as cornices and avalanche risks in those areas affected by snow and strong winds".
Meteogroup's Laura Caldwell said temperatures are set to remain low tonight, dropping to -4C as the evening draws in.
"It will be pretty similar conditions to those we have been having, staying cold and with quite a bit of cloud around with a few light snow showers," she said.
"But not adding to the snow we already have and nothing like we had before. It will tend to die out overnight but there will be a few more snow flurries over the course of the week.
"Tuesday's temperatures will not be much above 2 or 3C with pretty consistent temperatures going forward."
Estimates suggest that up to 10,000 animals have been buried beneath snowdrifts which reached up to 18ft (5.5m) high in parts of Counties Antrim and Down.
Agriculture Minister Michelle O'Neill said: "What we have done is we have asked the MoD to provide a helicopter because there was no helicopter available anywhere on this island that would be capable of taking the feed up and distributing it.
"We put a call into Theresa Villiers, the British Secretary of State, and asked for the MoD helicopter which could provide the service. They have agreed to come in and there were talks late into the night last night to make sure everything was ready to go."
Farmers have been particularly badly hit by the severe weather - suffering livestock fatalities and damaged properties. There have been calls for a compensation package to be agreed.
Ms O'Neill said she would press for a hardship payment for farmers at a ministerial Executive meeting on Thursday.
The number of animals killed by the freak weather is unclear.
The emergency services, Red Cross, RAF and others are co-operating to provide basic supplies like bread and milk to people snowed in for days.
More than 140,000 Northern Ireland Electricity (NIE) customers who lost power when the wintry blast struck the eastern counties of the region last Thursday and Friday have since had supply restored.
For updates on road closures and weather follow us on Twitter at @BelTel
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