The Halifax born Irishman is believed to have tested positive for a banned substance, ephedrine after the play-off semi-final second-leg win over Preston at Bramall Lane.
The keeper who has made over 250 appearances for the red and white wizards could face a lengthy ban.
A Sheffield United F.C. spokesman said: "We can confirm the Paddy Kenny has been suspended by the club. This is an ongoing, confidential matter and as such we are unable to comment any further."