He is the younger brother of fellow cyclist Dean Downing. He has competed largely on the UCI Continental Tour and in British Premier Calendar races. In addition to his national championships, he has also been successful in some multi-stage races.
His biggest victory to date has come in the 2010 Tour de Wallonie, a 2.HC class event, as well as the 2009 Tour of Ireland.
His contract was renewed for a further year, for the 2011 season. In November 2011 it was announced that his contract was not being renewed for a third year and he would join the British Continental Team Endura Racing.
Following the merger of Endura with Team NetApp Downing joined the NetApp-Endura squad for 2013. In September 2013 it was announced that Russell and Dean Downing would join the new NFTO cycling team for 2014.
Russell Downing signed for the Cult Energy Pro Cycling team for the 2015 season, but has returned to Britain with JLT–Condor for the 2016 season.