"Alex Txikon (Spain), Ali Sadpara (Pakistan) and Simone Moro (Italy) have reached the top of Nanga Parbat," Karrar Haidri, spokesman of the Alpine Club of Pakistan told AFP, confirming it was the first time the summit has been reached during winter months.
He said a fourth climber, Tamara Lunger of Spain, had been forced to halt the climb some metres beneath the summit.
At 8,125 metres (26,660 feet) Nanga Parbat is the world's ninth highest mountain. It earned its grisly nickname after more than 30 climbers died trying to conquer it before the first successful summit in 1953.
Its fearsome Rupal Face, rising more than 4,000 metres from base to top, presents one of the most difficult - and tantalising - challenges in climbing.
The climbers will spend Friday night at Camp 4 at 7,200 metres, and return to base camp tomorrow, Haidri said, adding that only then will they have completed the ascent.
Twitter was abuzz with the feat as fans hailed and congratulated the climbers - including Moro, one of the world's leading Alpinists, who was among those to return unsuccessful from an attempt to scale Nanga Parbat in 2014.
"We, Simone and Tamara's team, want to say that we are HAPPY & PROUD of the all 4 athletes!!! And we look for a direct contact to them when they will be at C4," said a statement on Moro's Facebook page.
In 2013 gunmen shot dead nine foreign climbers and their Pakistani guide at the Nanga Parbat base camp - one American with dual Chinese citizenship, two other Chinese, three Ukrainians, two Slovakians, one Lithuanian and one Nepalese. A Pakistani guide was also killed.
Northern Pakistan is a magnet for mountaineers and is home to some of the tallest mountains in the world, including K2 - at 8,611 metres, the world's second highest peak, but often deemed a more challenging climb than the highest, Mount Everest.
Nestled between the western end of the Himalayas, the Hindu Kush mountains and the Karakoram range, Gilgit-Baltistan houses 18 of the world's 50 highest peaks.
It is also home to three of the world's seven longest glaciers outside the polar regions. Hundreds of its mountains have never been climbed.