Playing as a Forward, Nakayama made his J1 League debut on 11 March 1994. From then until 2009, he was an ever-present part of the Júbilo Iwata lineup as they were consistently one of the top teams in the J1 League since its inception. With a strike-rate of more than a goal every two games throughout his career, Nakayama was the inspirational and talismanic leader for both Júbilo Iwata and the Japanese national team. At the 1998 World Cup finals in France, Nakayama scored the only goal of the tournament and the first goal for Japan in the history of the World Cup against Jamaica on 26 June 1998. He has scored 21 goals in 53 appearances for the Japanese national team. Nakayama also holds the world record fastest hat-trick at international level. He managed three goals in an 2000 Asian Cup qualification match against Brunei on 16 February2000 in only three minutes and three seconds, beating the previous record of Englishman Willie Hall set in 1938 by 27 seconds. This striker becomes a record-holder with other hat-tricks, that he did it in four successive games of J1 League, from 15 to 29 April in 1998. He scored 16 times in these games. The record is recognized by the Guinness Book of World Records Affectionately known as "Gon Nakayama" is a fan favorite among many casual Japanese football fans for his outspoken and humorous nature. Now in the twilight of his career, injuries and age have taken a toll on Nakayama's skills but he still remains a favorite of the Jubilo faithful, as evidenced by the fact that he draws the loudest cheers by far from the home crowd at Yamaha Stadium when his name is announced during warm-ups or when he comes on as a substitute. On 4 December 2012, he announced his retirement at the age of 45, citing injuries to his both knees, after being J1 League's all-time leading scores of 157 goals. In September 2015, he began to train with Azul Claro Numazu and then he signed a contract with the Japan Football League team Azul Claro. Despite the fact he didn't play any minute of JFL with Azul Claro, his contract was renewed for 2017 season, a first for a professional football club.
Nakayama is currently the all-time top goal scorer in J1 League with 157 goals. He holds the record for top scorer in a single season, scoring 36 goals in 1998.
Nakayama once portrayed himself on television, performing voice work for a guest role on the anime.
Nakayama appeared on the front cover of the Japanese releases of Konami's Winning Elevenvideo game series in 2002 and 2003.
He married actress Tomoko Ikuta in 1996, and together they had a daughter. Ikuta did the voice-over for lead actress Lee Young-ae in the Japanese version of the popular South Korean TV series Dae Jang Geum.
