Riesberg took office as commissioner of insurance in 2011 and stepped down in 2013. He was appointed by Governor John Hickenlooper. As the commissioner serves at the governor's pleasure, Riesberg was not subject to reappointment until a new governor is elected.

Before becoming commissioner, Riesberg was a member of the Colorado House of Representatives, having represented District 50 from 2004 to 2011.