The deal is worth $31.5 million, according to the team.
Ibanez will likely replace Pat Burrell as the everyday leftfielder for the defending World Champs.
The 36-year-old lefty batted .293 last season with 43 doubles, 23 homers and 110 RBI in while playing all 162 games with the Seattle Mariners.
The Phillies hope that Ibanez keeps up his trend of batting better against lefties than righties so that the lineup already packed with the left-handed bats of Chase Utley, Ryan Howard and others can remain balanced.
Jersey alert -- Ibanez will rock No. 29 for the Phils.
He will be officially introduced by the team Tuesday afternoon at a press conference.