Stefano Bianco comes from a family of motorcycle fanatics and launched his racing career with third place in the European minibikes series in 1998. In 2000 he contested the Aprilia Challenge alongside his brother, taking three podium finishes from six races and making the step up to 125cc with his World Championship debut as a wildcard in Australia.

In 2002 he participated in his first full season in the class alongside Italian compatriot Max Sabbatani, and finished a respectable 19th overall. In the following years lack of form and injuries, such as those suffered in a serious accident during a test in Jerez in 2005, have hindered Bianco. Indeed, his seventh place finishes in the French and Catalonian rounds of 2002 remain his best results to date.

He rode for the first half of the 2008 campaign with the WTR San Marino Team, but did not complete the season. Bianco returns to the 125cc World Championship full time in 2009 riding for the CBC Corse team alongside Marco Ravaioli.