The eclectic collection featured hundreds of items in a range of prices - from a masterpiece portrait by Peter Paul Rubens to horse carriages, dishes and jugs.
All the items offered at the three-day sale once belonged at Althorp House, the Spencer family's country estate in Northhamptonshire, and in Spencer House, their historic London home. While none of the lots were owned by Diana, many have been in her family for centuries.
Althorp was where Diana's grew up and became the site of her burial following her death in 1997 in a car crash in Paris. The estate is now occupied by Diana's brother, Earl Charles Spencer.
At the top of the price range was Rubens' "Commander Being Armed for Battle," which sold for USD 14 million at Christie's Old Masters sale on Tuesday. The Spencer family had owned it since 1802.
About a dozen horse-drawn carriages were on offer, and one - The Spencer State Chariot, used at the coronation of King Edward VII in 1902 - was sold for USD 202,000.
There were more affordable items, too. A sword stand was sold for USD 228, while a piece of wood - said to be the only piece saved from the stables at Spencer House - went for the same price. Those stables were bombed during World War II, Christie's said.
The auction house said the sale attracted heavy international demand from clients who bid on the Internet, including some from China, Albania and Kazakhstan.