The 25-year-old, who was selected in the 2009 rookie draft, has played 39 games in his four seasons at Fremantle.
Freo general manager of player management Brad Lloyd said it was pleasing to sign the 192cm defender.
“Alex has become a very dependable defender for the football club,” he said.
“We’re excited that he’s extended his contract for another year.”
Young talls Tanner Smith and Matt Taberner have also agreed to contract extensions.
Smith, who was selected with pick 36 in the 2012 National Draft, signed a one-year extension to the end of the 2015 season.
The 19-year-old debuted in round 4 this year before a shoulder injury ruled him out for the remainder of the season.
Taberner, 20, hails from country Victoria and came to the club via the 2012 rookie draft.
He signed a two-year extension until the end of season 2015 and will be added to the senior list.
The 197cm forward debuted in round 13 against North Melbourne and has played four games in his first AFL season.
Lloyd said both key position players had enjoyed solid first seasons of AFL.
“They’re important players for us in the future and form an important part of our list management model,” he said.
