Clarke, 23, has filled in admirably as lead ruckman this season since returning to the side in round 8 against Sydney at the SCG.
Originally from the Oakleigh Chargers in Victoria, he was selected by Fremantle in the 2008 National Draft with pick 37 and made his debut in round 13, 2009, against Collingwood at the MCG.
General manager of player management Brad Lloyd said the club saw Clarke as a valuable squad member and an important part of Freo’s future.
"We’ve been very pleased with Zac’s development," Lloyd said.
"He's been very solid since returning to the team this season and he has performed well in the ruck in the absence of Aaron Sandilands and Jon Griffin.
"We're very happy to have him stay at Fremantle."
Clarke said he was rapt to sign on for two more years, with the progress the side had made under senior coach Ross Lyon a major selling point in his decision.
“To get to play another two years under Ross and with the boys, I’m stoked,” he said.
Clarke admitted he had given the decision on his new contract plenty of thought and flew to Melbourne during Fremantle’s bye week to discuss his future with his family.
“They were just happy to back me in and they’re really rapt for me,” he said.
“I had to discuss it with them first, but in the end, the way the team is going, and the coaches and playing group we have, it really wasn’t a tough decision.”
Clarke has played 40 career games and kicked 22 goals.
