It was expected to fetch between $1.1 million to 1.5 million.
The buyer was a private American collector. The painting, featuring brilliant tones of blue and green and measuring 22 by 22 inches, is one of only four "Flowers" paintings from this year recorded by The Andy Warhol Foundation archive. This is a record price for a 1978 "Flowers" painting, the auction house said.
The work had been in a private German collection for many years.
"This sale confirms what we have maintained for a long time at artnet -- that art buyers are willing to buy high-end artworks online," Hans Neuendorf, the company's chief executive officer, said in a statement.