He made his UEFA Cup debut against French side Auxerre, coming on as substitute for Arkadiusz Malarz after he had been injured, but only nine minutes later, Cierzniak was sent off for professional foul.

Cierzniak made his Lech Poznán debut in the UEFA Intertoto Cup in a 3–1 loss against Tiraspol on 8 July 2006.

Three season later, Cierzniak lost his first team place to Zbigniew Małkowski, which resulted in him leaving the club when his contract expired on 31 December 2010.

Cierzniak agreed a two-year contract with Scottish Premier League club Dundee United in February 2012, due to start in the summer.

Upon signing the new contract, United Manager Jackie McNamara said on the club's website: "This extension is merited because Rado has shown that he is an excellent SPL goalkeeper.