Nyong'o made an acclaimed feature film debut in slavery epic "12 Years a Slave," while Seydoux plays half of a young French lesbian couple in the Cannes festival prize-winner.
Other finalists announced Monday include American actor Dane DeHaan, who plays a troubled poetic muse in Beat Generation saga "Kill Your Darlings."
Two British actors round out the list - George MacKay, who stars in Proclaimers musical "Sunshine on Leith," and Will Poulter of comedy "We're the Millers."
The winner will be decided by public vote and announced during the British Academy Film Awards - Britain's equivalent to the Oscars - on Feb. 16.
