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Success and repeats

The 1954 Italian expedition finally succeeded in ascending to the summit of K2 via the Abruzzi Spur on 31 July 1954. The expedition was led by Ardito Desio, and the two climbers who reached the summit were Lino Lacedelli and Achille Compagnoni. The team included a Pakistani member, Colonel Muhammad Ata-ullah, who had been a part of the 1953 American expedition. Also on the expedition were Walter Bonatti and Pakistani Hunza porter Amir Mehdi, who both proved vital to the expedition's success in that they carried oxygen tanks to 8,100 metres (26,600 ft) for Lacedelli and Compagnoni. The ascent is controversial because Lacedelli and Compagnoni established their camp at a higher elevation than originally agreed with Mehdi and Bonatti. It being too dark to ascend or descend, Mehdi and Bonatti were forced to overnight without shelter above 8,000 metres (26,000 ft), leaving the oxygen tanks behind as requested when they descended. Bonatti and Mehdi survived, but Mehdi was hospitalised for months and had to have his toes amputated because of frostbite. Efforts in the 1950s to suppress these facts to protect Lacedelli and Compagnoni's reputations as Italian national heroes were later brought to light. It was also revealed that the moving of the camp was deliberate, a move apparently made because Compagnoni feared being outshone by the younger Bonatti. Bonatti was given the blame for Mehdi's hospitalisation.

On 9 August 1977, 23 years after the Italian expedition, Ichiro Yoshizawa led the second successful ascent, with Ashraf Aman as the first native Pakistani climber. The Japanese expedition took the Abruzzi Spur and used more than 1,500 porters.

The third ascent of K2 was in 1978, via a new route, the long and corniced Northeast Ridge. The top of the route traversed left across the East Face to avoid a vertical headwall and joined the uppermost part of the Abruzzi route. This ascent was made by an American team, led by James Whittaker; the summit party was Louis Reichardt, Jim Wickwire, John Roskelley, and Rick Ridgeway. Wickwire endured an overnight bivouac about 150 metres (490 ft) below the summit, one of the highest bivouacs in history. This ascent was emotional for the American team, as they saw themselves as completing a task that had been begun by the 1938 team forty years earlier.

Another notable Japanese ascent was that of the difficult North Ridge on the Chinese side of the peak in 1982. A team from the Japan Mountaineering Association led by Isao Shinkai and Masatsugo Konishi put three members, Naoe Sakashita, Hiroshi Yoshino, and Yukihiro Yanagisawa, on the summit on 14 August. However Yanagisawa fell and died on the descent. Four other members of the team achieved the summit the next day.

The first climber to reach the summit of K2 twice was Czech climber Josef Rakoncaj. Rakoncaj was a member of the 1983 Italian expedition led by Francesco Santon, which made the second successful ascent of the North Ridge (31 July 1983). Three years later, on 5 July 1986, he reached the summit via the Abruzzi Spur (double with Broad Peak West Face solo) as a member of Agostino da Polenza's international expedition.

The first woman to summit K2 was Polish climber Wanda Rutkiewicz on 23 June 1986. Liliane and Maurice Barrard, who had summited later that day, fell during the descent; Liliane Barrard's body was found on 19 July 1986 at the foot of the south face. On July 28, 2024, Japanese climber Naoko Watanabe became the first woman to summit K2 three times.

In 1986, two Polish expeditions summited via two new routes, the Magic Line and the Polish Line (Jerzy Kukuczka and Tadeusz Piotrowski). Piotrowski fell to his death as the two were descending.

Thirteen climbers from several expeditions died in the 1986 K2 disaster. Another six mountaineers died in the 1995 K2 disaster, while eleven climbers died in the 2008 K2 disaster.