The scheme has been led by the Mourne Heritage Trust and the money comes from the Landscape Partnership  programme which helps to protect treasured landscapes.
Meanwhile, £1,040,200, is going towards the Ring of Gullion area in Armagh.
The news has been welcomed by Environment Minister Alex Attwood.
"This is great news for two of our most prized landscapes, Mourne and the Ring of Gullion, both of which are designated Areas of Outstanding Natural Beauty," he said.
"It is clear evidence of the growing recognition that investing in our natural and built heritage can produce very significant community benefits as well as a sound economic return."
Head of Heritage Lottery Fund Northern Ireland Paul Mullan said he was delighted at the news.
"The Mournes are one of the most iconic landscapes of such natural beauty we cherish in Northern Ireland," he said.
"They are subject to a high number of designations for their heritage value such as Special Area of Conservation (SAC), Area of Special Scientific Interest (ASSI) and contain some of Europe's most important tracts of upland heath.
"This scheme will ensure long-term management, promising long-term benefits for the local communities, visitors to the Mournes and to the heritage of this magnificent landscape."
Martin Carey of the Mourne Heritage Trust said the funding would "celebrate and significantly enhance the conservation of our natural, built and cultural heritage".
Thirty individual projects make up the Landscape Conservation Action Plan which covers an area of 223km².
Among the plan's objectives are encouraging healthy heathland;  caring for walls and monuments; making recreation sustainable; developing trails with tales; getting people around the Mournes;  participative research and learning and sharing stories.
One of Northern Ireland's main tourist attractions, the Mourne Mountains, have received £1.5m from the Heritage Lottery fund.