"This is only the second time a Tintin plate has exceeded a million euros," Eric Leroy, comic book expert at French auction house Artcurial, said.
A double page plate also from King Ottokar's Sceptre was sold for more than 1.5 million euros at Sotheby's in Paris in October.
Artcurial had estimated Saturday's lot would fetch between €600,000 and €800,000, before fees.
"Herge's universe still conquers," added Leroy, referring to the cartoonist behind the famous comic.
French singer Renaud
The work in blue watercolor, gouache and ink was bought on the phone "by a European collector, a long-time fan", said Leroy.
Published in 1939, King Ottokar's Sceptre is the eighth instalment of the adventures of the intrepid boy reporter by the Belgian artist Herge.
Intended by Herge as criticism of Nazi Germany, Tintin helps thwart a plot to overthrow the king of a fictional Central European country which is threatened by an aggressive neighbour.
Tintin works are becoming increasingly popular with collectors.
An ink drawing for the cover pages of the Tintin books published from 1937 to 1958 was sold for 2.65 million euros by Artcurial in 2014, a world record.