"We had a meeting (on Monday night) and the word came through that the transfer was signed, that he is coming back to Ballyroan Abbey," confirmed club chairman Eamon Mulhall.
"The club is delighted because we were fairly depleted in the past few years ... he is one of the main players and is performing well with the county at the moment."
According to a Parnells spokesperson, Tierney has submitted a transfer request but this had yet to be received by the northside club. The player himself could not be contacted.
Reflecting on how their freetaker initially moved to Dublin on account of work, Mulhall added: "I'd say his heart is in the local club and that is why he is coming back."
The exodus of high-profile Laois players to Dublin clubs has been a source of huge local annoyance, with four county stars (Darren Rooney, Colm Parkinson, Colm Begley and Tierney) joining Parnells alone in recent years.
Parkinson subsequently transferred back to Portlaoise and now Tierney is set to make the same homeward journey.