Prinsloo, wearing only a Speedo costume, cap and goggles, swam a time of 1:23:48 - nine minutes faster than the previous record held by German elite swimmer Christof Wandratsch (1:33:11) set in 2005.
Prinsloo recently placed a close second behind four time winner Chad Ho at the world's biggest open water swim, the Midmar Mile and has his sights set on the 10km race at the Rio Olympics in 2016. He placed 12th in the 10km at London 2012.
Seconded by world renowned, veteran cold water swimmer, Ram Barkai who has mentored him in coping with icy water, Prinsloo set off from Robben Island on Wednesday morning at a lighting pace. He slowed down after 3km due to the impact of the cold water which averaged around 15°C.
"It looked like a record swim from the outset. But, Robben Island is a tricky crossing and the currents and the cold have broken many experienced swimmers," said Barkai.
"The final push came in the last 1.5km when I held aloft a white board stating: 'Record Time, GO, GO, GO!.' Troy squeezed a big grin, put his head down, and sped up. What an awesome day for South Africa - the record is back in our hands thanks to Troy." Barkai exclaimed.
Prinsloo said he was "over the moon."
"I'm very happy with this achievement. Conditions were good and I gave it my best. I want to thank everyone who assisted, particularly Speedo for backing me."
Speedo SA's brand president Stuart Hopwood said he was thrilled with Prinsloo's record saying he was an inspiration. "We salute Troy for yet another great accomplishment and pledge our ongoing support to him and other South Africans who continue to push the envelope in world class fashion."