Contareno offers his daughter Bianca in marriage to Capellio, a member of a rival clan, in an act of conciliation meant to end a long-standing family feud.

News arrives that Falliero has been captured and must stand trial for treason, allegedly for his contacts with a foreign power because he was found hiding in the Spanish Embassy.

The quartet during the trial scene, Cielo, il mio labbro ispira, was reworked several times by Rossini over the years, and its popularity eventually outlasted that of the opera itself.

In the sixteenth chapter of his essay On Love, he wrote that : "A sad and tender tune, provided that it is not too much dramatic, that imagination is not forced to consider action, as it entice oneself only to the daydreaming of love, is a delightful thing for miserable and tender souls; for instance the clarinet's prolonged part, at the beginning of the Bianca e Faliero [sic] quartetto, and the Camporesi's story around the middle of the quartetto."

[5] The composer reused music from the rondo finale of his recent, well-received opera, La donna del lago in this work as well.