The striker had joined the Welsh side mid-way through the 2014/15 season, after an impressive start to the season with League One side Chesterfield.
The Irishman scored 25 goals in 33 appearances for the Spireites during the 2014/15 season, before signing for the Bluebirds until the summer of 2018.
Doyle now joins North End on their return to the Championship, and his arrival provided manager Simon Grayson with even more fire power at the top end of the pitch.
The 27-year-old started his career over in Ireland, enjoying spells at Shelbourne, Shamrock Rovers and Sligo Rovers, before joining Scottish side Hibernian in 2011.
After spending two years at Hibs, Doyle joined Chesterfield in the summer of 2013, and won promotion to League One, scoring 13 goals in all competitons in his first season with the Club.
Doyle scored four times while on loan at Deepdale last season, and will be looking to increase his tally in the coming season after a full pre-season with the squad.