According to Christie's, the price exceeded 1 million dollars pre-sale estimate and topped 6 million dollars when the commission is included.
Christie's said that the price is now a record for a letter sold at auction eclipsing an Abraham Lincoln letter which was sold in April 2008 for 3.4 million dollars including commission, Fox News reported.
On Thursday, the molecular biologist's 1962 Nobel Prize medal in physiology or medicine will be offered by Heritage Auctions, which estimates that it could fetch over 500,000 dollars.
In the March 19, 1953, handwritten letter to his 12-year-old son, Michael, Francis describes his discovery of the structure of DNA as something "beautiful."
The note tells Michael how he and James Watson found the copying mechanism "by which life comes from life." The letter includes a simple sketch of DNA's double helix structure, which Francis concedes he can't draw very well.
The seven-page letter, written to his son in boarding school, concludes with "Read this carefully so that you will understand it. When you come home we will show you the model. Lots of love, Daddy."
Francis, who died in 2004 at age 88, won the Nobel Prize along with Watson and Maurice Wilkins.