The portrait of Mandela, who raised concerns about his health after being hospitalised with a lung infection in March, is 4.2m x 4.2m and is priced at R2.75m.
The portrait took 14 months to complete and consists of acrylic paints on nine individual canvasses.
Blomkamp told Huffington Post that he "wanted to capture Mandela's legendary smile in perpetuity. He has one of the most captivating faces I have seen."
Blomkamp created this painting, together with paintings of Oprah Winfrey and Richard Branson to launch his "Mandela Head in the Karoo" Project, he said on his Facebook page.
The project is set to measure 50x50km and will consist of millions and millions Karoo schrubs planted and arranged "as to exactly replicate the face of Mandela".
"It will endure as a living memorial to the qualities this great man has shared so uniquely with the World. The 'HEAD' will also be viewed from space and images will be constantly relayed back to Earth to provide an ongoing animated image of Mandela's face that will last for as long as our Planet spins in our Universe."
At the age of 19, Blomkamp was commissioned to produce the (then) largest stained glass window in the world and has gained fame for his stained glass work on sky scrapers and churches in the Gauteng area.
The portrait of Nelson Mandela is being sold via VeryFirstTo in London.
In the photo below, Blomkamp stands next to the finished work of his Nelson Mandela portrait:
