Du Preez played a central role in the Boks' series triumph over the Lions this summer as Peter de Villiers' men emerged as narrow winners in Durban and Pretoria.
The 27-year-old then continued to impress as his country claimed their first Tri Nations crown since 2004 thanks to three successive victories over the All Blacks and a brace of wins over the Wallabies.
Du Preez also picked up a Super 14 winners medal with the Bulls before experiencing Currie Cup glory with the Blue Bulls last weekend.
And, having won every conceivable piece of silverware so far this year, du Preez has now given the ultimate individual honour by his country's rugby journalists.
"They were any number of outstanding Springbok performers who could have been among the nominations," said Mark Alexander, deputy president of the South African Rugby Union.
"It's a tribute to the sustained excellence of Fourie's play that he was chosen by the media for this prestigious award.
"There are very few players in world rugby who can claim to be as influential as he is."
Morne Steyn, the Bulls fly-half who kicked the Boks to victory over the Lions at Loftus Versfeld, was named Players' Player of the Year, as well as Test Player of the Series against the Lions.
Cheetahs flanker Heinrich Brussow picked up the SA Rugby Young Player of the Year award for performances in his debut international season.
Brussow was also named Provincial Player of the Lions Series, following his performance for the Cheetahs during the Lions' narrow win in Bloemfontein.
SA Rugby award winners
SA Rugby Player of the Year - Fourie du Preez
Players' Player of the Year - Morné Steyn
SA Rugby Young Player of the Year - Heinrich Brüssow
Test player of the Castle South Africa 2009 Lions Series - Morné Steyn
Provincial player of the Castle South Africa 2009 Lions Series - Heinrich Brüssow
SA Rugby Team of the Year - The Springboks
Absa Coach of the Year - Peter de Villiers
Vodacom Super 14 Player of the Year - Morné Steyn
Absa Curie Cup Premier Division Player of the Year - Luke Watson
Absa Curie Cup First Division Player of the Year - Allistair Kettledas
SuperSport Try of the Year - Jaque Fourie, 2nd Test vs Lions