Professional since 2005, in the same year he won his first pro race at Tour of Qinghai Lake in China. From 2008 to 2012, he wore the green and white jersey of the Italian team Liquigas and at the Giro d’Italia 2010 wore, for three days, the white jersey for best young rider.
From 2013 he raced for the Kazakh Astana Pro Team always next to his captain and best friend Vincenzo Nibali contributing to the victory of the Giro 2013 and in other many races. During 2016, he wore the leader's jersey in the Giro del Trentino after winning the Team Time Trial and has participated at the edition of Giro d’Italia where he had to abandon due to a bad fall in the last kilometers of the eleventh stage.
Earlier, in February, he had been part of the team that won the Tour of Oman and the last October has made a great contribution in the victory of Abu Dhabi Tour. As one of Nibali's trusted Grand Tour domestiques, Valerio Agnoli joined together with him BAHARAIN MERIDA Pro Cycling Team since the foundation. He showed to be one of the most loyal teammates in the peloton, a classy rider who helped wherever and always delivered what is asked of him.