Ito, the sixth Japanese to win the honour likened to a Nobel Prize for architecture, said Monday that the field needs to evolve to suit changing times, to "be more open to nature."
"Architects have made architecture too complex. We need to simplify it and use a language that everyone can understand," Ito said at one of his offices in Tokyo, a strictly functional place whose only frills were the lavish bouquets of orchids, lilies and other blooms sent to congratulate him for the award.
Ito's buildings, from libraries and theatres to offices and homes, have won praise for their fluid, airy beauty and balance between nature and function, the physical and virtual worlds.
Among the best-known works are the spiral White O residence in Marbella, Chile, the angular 2002 Serpentine Gallery Pavilion in London and the arch-laced, curving Tama Art University in suburban Tokyo.
Architecture needs to change to suit changing needs brought on by declining populations, climate change and scarce resources, he said, likening a more sustainable design approach to the growth of a tree, which expands, branch by branch, in relation to the light and its surroundings.
"We have to base architecture on the environment. Whatever age it is, people are people," he said. "I want it to be fresh."
The Sendai Mediatheque is a library transparent even down to the internal tubes used for its ventilation and wiring — like the tubes in a human body, he says — was lauded for withstanding the massive earthquake that struck offshore from the city in northeastern Japan in March 2011.
Ito had been working as an architect for 30 years when it opened in 2001.
"That was the time I really felt I was glad to have become an architect," he said. "It is like a wall-less gallery space, where people are able to walk around. You often see people taking naps or couples behaving if they are on dates."
Though the Sendai structure is boxy in design, many of his works are enlivened with webs, arches and curbs that enliven and deflect the traditional grid structure that underlies most modern buildings.
Ito has been involved in several projects aimed at aiding survivors of the 2011 earthquake and tsunami disasters, which killed nearly 20,000 people and left tens of thousands homeless. The aim is to create communal spaces where residents displaced to temporary housing units can chat and find connections with their neighbours, he said.
U.S. Supreme Court Justice Stephen Breyer, who served on the Pritzker Prize jury, praised Ito for improving the "quality of both public and private spaces."
"His buildings are complex, yet his high degree of synthesis means that his works attain a level of calmness, which ultimately allows the inhabitants to freely develop their life and activities in them," said another jury member, Chilean architect Alejandro Aravena.
Other recipients of the Pritzker have included masters such as Frank Gehry, I.M. Pei, Tadao Ando, Renzo Piano and Wang Shu.
In accepting the prize, Ito said he was determined to "never fix my architectural style and never be satisfied with my works." Completing a work, Ito said, makes him "painfully aware of my own inadequacy, and it turns into energy to challenge the next project."
Ito began his career at Kiyonori Kikutake & Associates after he was graduated from Tokyo University in 1965. He founded his own firm in 1971. His works have been exhibited in museums in the United States, England, Denmark, Italy, Chile and numerous cities in Japan.
He will receive a $100,000 grant and a bronze medallion at the formal Pritzker ceremony May 29 at the John F. Kennedy Presidential Library and Museum in Boston.
Sponsored by the Hyatt Foundation, the Pritzker Prize was established in 1979 by the late entrepreneur Jay A. Pritzker and his wife, Cindy, to honour "a living architect whose built work demonstrates a combination of those qualities of talent, vision and commitment, which has produced consistent and significant contributions to humanity and the built environment through the art of architecture."
The Pritzker family founded the prize because of its involvement with developing Hyatt Hotel properties around the world and because architecture was not included in the Nobel Prizes. The Pritzker selection process is modeled after the Nobels.
AP Entertainment Writer Derrik J. Lang contributed to this report.