Finally settling on road cycling with Bridgestone Anchor in 2005, Miyazawa quickly established himself as one of Japan's top sprinters, reaching the podium not only in Japan, but in Asia and Europe as well.

He was hired by the UCI Professional Continental team Amica Chips-Knauf in 2009 but returned to his Japanese team when Amica Chips floundered due to financial difficulties.

Joining Team Nippo in 2010, he won the Japanese national championship that year.

On 28 October 2010, it was announced that Miyazawa had signed to ride with the new Italian Pro Continental team, Farnese Vini–Neri Sottoli, for the 2011 season.

[5] After his retirement, he assumed the post of manager of the Lemonade Bellmare cycling team.