Sakamoto co-founded the band Yellow Magic Orchestra, known as YMO, with Hosono Haruomi and Takahashi Yukihiro in 1978. The group pioneered the use of computers and electronic instruments such as synthesizers, establishing the genre called techno-pop.
Sakamoto's accolades include an Oscar and a Grammy for scoring the 1987 film "The Last Emperor."
The musician was diagnosed with throat cancer in 2014. He resumed his work in music after undergoing treatment. But in 2021 he disclosed that he had been diagnosed with rectal cancer.
His management agency said Sakamoto died on Tuesday.
The company issued a statement online saying, "While undergoing treatment for cancer discovered in June 2020, Sakamoto continued to compose in his home studio whenever his health would allow."
It says that Sakamoto "lived with music until the very end."
Sakamoto an activist and environmentalist
Sakamoto was also a prominent activist and supporter of environmental causes.
After the powerful earthquake and tsunami that hit northeastern Japan on March 11, 2011, he devoted himself to supporting the victims. Sakamoto served as music director of the Tohoku Youth Orchestra, which is made up of children from disaster-hit areas.
He also campaigned for the abolition of nuclear power plants and weapons, and he worked on environmental efforts including forest conservation.
In early March, Sakamoto sent a letter to Tokyo Governor Koike Yuriko expressing opposition to a redevelopment project in the capital that would demolish historic sports venues and tear down hundreds of trees. He wrote that "the trees should not be sacrificed."
Artists pay tribute
Prominent artists from around the world have been paying tribute to the late musician.
Suga, a member of K-pop super group BTS, took to Instagram to say, "Teacher, I hope the faraway journey is peaceful."
"Sad to see another force leave this planet," wrote US musician and producer Questlove on Instagram. He noted that artists across a range of genres cite Sakamoto as "their god."
Late musician David Bowie's Twitter account also shared a tribute with a picture of the two artists together.
They starred in the 1983 film "Merry Christmas Mr. Lawrence," for which Sakamoto composed the score.
Japanese actor and film director Kitano Takeshi, who also starred in the film, said on his website that the news of Sakamoto's passing was shocking and sad, adding that he has no words.