Ono grew up in the Shizuoka Prefecture and began his professional career with Urawa Reds in the J1 League in 1998. The same year, he became the youngest Japanese player to play at 1998 World Cup, at age 18. He caught the attention of foreign clubs with his performance at the 1999 World Youth Championship in Nigeria, where he captained the Japanese Under-20 side that reached the final. But later that year, he suffered a severe knee injury in a qualification match for the 2000 Olympics with Japan's Under-23 side, forcing him to miss the rest of the season and Olympic qualifying.