Lilywhites boss Stephen Kenny continues to build his squad ahead of the new season by recruiting the Bohs midfielder who becomes the former Shamrock Rovers boss's fifth signing
The 22-year-old had played for Bohs during the 2012 season and will enter into his second spell at Oriel Park, having spent the 2011 season with the Lilywhites.
Ward represents Stephen Kenny's fifth signing since taking over the reins of the club in November 2012. He joins John Mountney and Eoghan Osbourne, who have extended their stay, as well as new signings Patrick Hoban and John Dillon.
Meanwhile Sligo Rovers have secured the signature of forward Raffaele Cretaro, who becomes Ian Baraclough's fourteenth signing of the 2013 season.
"I’m delighted to get things sorted and look ahead to the new season," Cretaro told sligorovers.com. "It can take time and it is nice to complete the deal.
"It is a great challenge for the club to keep on improving given what we’ve done in the past few seasons. It’s an exciting one and I can’t wait to get started again," he added.