The 1943 oil painting Tower of the Koutoubia Mosque is the only painting Churchill painted during World War II.
He then gave it to US President Franklin D Roosevelt as a birthday present.
Auction company Christie's had calculated the price at 1.5-2.5 million pounds, but that assessment came to shame after Monday night's intensive bidding.
The seller was the American actress Angelina Jolie who received the painting as a wedding gift from her ex-husband and actress Brad Pitt.
"In love with the light"
Christie's calls the painting Churchill's most important work ”.
"He first visited Morocco in 1935 and fell in love with the light," says Nick Orchard, director of modern British art at Christie's in London.
The British Prime Minister was a passionate landscape painter.
Marrakesh was his favorite place and he returned to the city on six occasions.
Two more paintings by Churchill (1874–1965) were auctioned off.
In total, Churchill's paintings raised £ 9.4 million.