Radiohead’s most commercially successful album released in 1997 was OK Computer.
OK Computer is Radiohead’s third studio album and was released on May 21, 1997. It followed The Bends and marked a major artistic shift for the band, combining alternative rock with electronic textures, unusual song structures, and themes about technology, alienation, consumerism, and modern life.
The album became Radiohead’s first number-one album in the United Kingdom and achieved major international success despite the record label initially viewing its experimental sound as commercially risky. Its singles included “Paranoid Android,” “Karma Police,” and “No Surprises.” The album’s critical reputation grew alongside its sales, and it is now frequently regarded as one of the defining records of the 1990s.
Kid A was released later, in 2000, so it cannot be the answer to a question specifying 1997. The Bends came out in 1995, while Pablo Honey was Radiohead’s 1993 debut. OK Computer is therefore both the chronological and canonical answer.