Superintendent David Taylor, a former head of the Garda Press Office, has been cleared of leaking sensitive information to the media.
He was suspended on suspicion of passing on details relating to the removal of two Roma children from their families in 2013.
He was arrested in 2015 and has been on a severely reduced salary while on suspension.
He is also at the centre of the ongoing whistleblower controversy after claiming senior Garda management directed him to spread malicious rumours about Sergeant Maurice McCabe.
Superintendent Taylor was told this afternoon that the DPP has decided not to prosecute.
Speaking after being informed of the decision, he says he has been through "an incredibly stressful and difficult time".
He has indicated he will be returning to duty shortly.
