The new deal sees Mzungu, who was previously contracted until the end of the 2013 season, tied to the club until the end of 2015.
Mzungu's signature follows the re-signings of young midfielders Hayden Crozier and Cam Sutcliffe last week.
Fremantle general manager of player management Brad Lloyd said the club was keen to continue to bolster its list.
"Retaining our talent is a major focus, and we see Tendai as an important member of our squad," Lloyd told fremantlefc.com.au.
"He started his AFL journey late, but since the day he arrived at Fremantle he's been outstanding with his commitment to his football.
"We're excited to keep him at the club for a minimum of another two years."
Fremantle drafted Mzungu in a pre-draft trade with Gold Coast in 2010. That followed a consistent season with WAFL club Perth the year before, in which he won the club's best and fairest.
The 27-year-old has played 45 of a possible 46 games since making his debut in round nine of the 2011 season.
Along with Crozier and Sutcliffe, Mzungu joins experienced trio Michael Johnson, Chris Mayne and Zac Dawson who have recently recommitted to Freo.
