The 35-year-old, who has previously stated he would retire if he failed to earn a new deal, has scored 209 tries in 311 games for the Giants since 2010.
McGillvary helped Huddersfield to League Leaders' Shield glory in 2013 and appeared in last season's Challenge Cup final.
The winger was named in the 2015 Super League Dream Team and earned 21 international caps during his time with the Giants.
Huddersfield have called on the club’s supporters to help give McGillvary, as well as Chris McQueen who is retiring at the end of the season, a fitting send-off in the final match of 2023.
"Jermaine McGillvary provided the Cowbell Army with memories to last a lifetime over his time at the club," read a statement.
"We believe it's only right that we turn out in numbers vs Warrington Wolves in our final game of the season to ensure that Jermaine can enjoy the best farewell possible from a club he has given his whole career to.
"Thank you, Jermaine McGillvary, a true Huddersfield Giant."