Pyatov started his career in Vorskla Poltava in 2002. He was bought by Shakhtar from Vorskla for approximately £880,000 on 13 December 2006. He spent the rest of the 2006–07 season on loan at Vorskla Poltava. In the 2007–08 season, Pyatov replaced Bohdan Shust as the main goalkeeper of Shakhtar Donetsk, playing in league, cup, and UEFA Champions League matches, keeping two clean sheets. For the 2008–2009 season Pyatov will have serious competition for his No.1 spot as Shakhtar loaned out Bohdan Shust, and signed FC Kharkiv 'keeper Rustam Khudzhamov who is reaching his prime and saved FC Kharkiv from relegation. But after Shakhtars' 2–0 loss to FC Lviv, Pyatov regained his place as the clubs' No.1. In a home Champions League fixture against Barcelona Pyatov made 7 crucial saves as Shakhtar were leading 1–0, until Bojan Krkić sent in a cross which was spilled by Pyatov for Lionel Messi to easily tap in to make it 1–1 in the 85th minute. But things went from bad to worse as another cross was sent in Messi rose and headed home giving Barcelona the win, and ruining Pyatov's perfect game. Pyatov has cemented his spot as Shakhtar's No.1 after great performances in the 2008–09 UEFA Cup which saw Shakhtar reach the final, beating fellow Ukrainian giants Dynamo Kyiv in the first ever all Ukrainian semi-final. His appearance in the final was marred as he spilled Naldo's freekick into the net to give Werder Bremen an equaliser but Shakhtar won 2–1 in extra time. On 1 November 2009 vs Chornomorets Odessa Pyatov played his 100th game for Shakhtar (conceding 72 goals), and in this game he won the Man of the Match, and is also the 1st time coach (Mircea Lucescu) ever named a goalkeeper Man of the Match.