Hughes, a box-to-box midfielder, has spent the past two seasons with Adelaide while in 2008 he scored a goal for Irish team Drogheda United against Dynamo Kiev in a Champions League qualifier.
“Adam brings strength to the midfield, something I feel we missed last season,” Ferguson said.
“He’s big and aggressive, he’ll bring a bit of bite to our team and he’s a winner.
“Adam is also a goal scorer, highlighted by the 13 goals he scored when used as a box-to-box midfielder in Ireland.”
Hughes is the seventh new player to sign with the club following the signatures of Danny Vukovic, Neil Young, Dean Heffernan, Evan Berger, Travis Dodd and Shane Smeltz.
“Ian Ferguson is rebuilding this squad with a lot of quality signings which is a real positive,” Hughes said.
“Obviously the results were not great last season so we need to work hard in the pre-season and work hard as a team to climb back up the ladder.”
Hughes will arrive in Perth this weekend with pre-season training to commence next week on Tuesday, May 3.
“I’m looking forward to it, a few boys will still be missing and we still need to finalise our squad but it’s an exciting time for our club and exciting for the new players coming in,” Ferguson added.