Whitfield has signed a seven-year deal, that will take him through to the end of the 2027 season.
The 25-year-old was set to be a free agent at the end of the 2020 campaign, but the new contract takes him off the market.
The speedy utility had a brilliant season in 2019, averaging 27.0 disposals, 7.7 marks, 3.6 inside 50s, 3.4 rebound 50s and 3.4 clearances per game.
— GWS GIANTS (@GWSGIANTS) December 8, 2019
“I’ve known my future is in Sydney for a long time,” Whitfield told the club’s website.
“I play for success and so being at the GIANTS is clearly the best option for me.
“As a club we’ve been in four finals in a row now and we’re a hungry group who continually drive each other to be better than the season before.
“This is an outstanding club with outstanding people and I’m excited to be here.”