Whitfield, from Kingston, Ont., is the most decorated triathlete in Canadian history, winning gold at the 2000 Sydney Olympics and silver at the 2008 Beijing Games. The 38-year-old was Canada's flag bearer at the 2012 London Games.
"Today marks the end of my career as a professional athlete; it's been an incredible journey and an amazing chapter in my life," said Whitfield in a release on his personal website. "I grew up dreaming of representing Canada at the Olympic Games, though I never imagined I would have the honour of wearing the Maple Leaf four times, winning two Olympic medals, and bearing the flag."
Whitfield also won gold at the 2002 Commonwealth Games in Manchester, U.K. and bronze at the 1999 Commonwealth Games in Winnipeg. He won 12 Canadian championships and earned 14 world cup victories.
He will now join Fantan Group — an international consultancy firm — and lead its new sports entertainment division in Victoria.
"It is time to shift gears. I have spent years with athletes of all ages — sharing — motivating — challenging," said Whitfield. "As part of the Fantan team, I have the ideal partnership to put much of what I've learned as a competitive athlete toward design and innovation in sports entertainment."
Many Canadian athletes tweeted their thanks and congratulations to Whitfield.
"Congrats to @simonwhitfield on an incredible career," said two-time Olympic gold medallist Catriona Le May Doan in a tweet. "Thanks for inspiring so many Canadians!"
Jayna Hefford, a four-time Olympic medallist with Canada's women's hockey team, echoed Le May Doan's sentiments.
"Sad to hear @simonwhitfield is retiring. What an incredible career! So many great memories watching him compete for #canada," said Hefford.
"Happy Retirement @simonwhitfield.Youve inspired so many,including me while making us all smile.Thanks4BeingU," said Canadian women's national soccer team member Karina Leblanc, including a picture of her and Whitfield in the tweet.