In the Venusberg, mythological figures cavort, until dismissed by the goddess Venus (mezzo-soprano), who is discovered holding the knight Heinrich (tenor) in her arms; he tells her that he wishes to return to the human world; she rebukes him and tries to keep him with her, but he calls upon the Virgin Mary, and she vanishes with the whole Venusberg. A young shepherd (soprano) sings a song of spring, and hails a chorus of pilgrims on their way to the "Festival of Grace" at Rome; Tannhäuser keels in gratitude at the foot of a wayside cross. There he is discovered by Landgraf Hermann (bass) and his attendant minnesingers, including Walther von der Vogelweide (tenor), Biterolf (bass), and Heinrich's best friend Wolfram von Eschenbach (baritone), all of whom urge him to return with them to the Landgrave's castle, the Wartburg; he is unwilling, until Wolfram reveals to him that his beloved Elisabeth has been mourning ever since his departure. Heinrich decides he must see her, and the others joyfully acclaim his return.
At the Wartburg, Elisabeth (soprano), rejoices that Heinrich is returning. Wolfram leads Heinrich to her; sadly reflecting that all hope of gaining her love is gone. The young men depart, and the landgrave calls on Elisabeth to greet the nobles, who are gathering that day for a song-contest. The landgrave proposes that the minstrels expound the nature of love in their songs: Wolfram sings of love as an inspiring spiritual force, but Heinrich, interrupting as if in a trance, sings of love being in essence a source of sensual delight and declares that only those know love, who have experienced it in the Venusberg. All but Elisabeth denounce him; the knights draw their swords — until Elisabeth interposes, calling on them to spare him, so his soul can be saved. Heinrich collapses in penitence; the landgrave commands him to seek pardon from the Pope, and the knights threaten him with death should he return unabsolved. The voices of the younger pilgrims setting out for Rome fill the hall; and Heinrich rushes out to join them.
A musical interlude depicts Heinrich's pilgrimage to Rome.
In autumn, Wolfram finds Elisabeth praying before the cross; they encounter the pilgrims returning from Rome, but Heinrich is not among them. Elisabeth departs to consecrate her death to Heinrich's salvation, renouncing all hope of human happiness. Wolfram, having called upon Heaven to accept Elisabeth (in his famous "Evening Star" song), is accosted by a dark figure. It is Heinrich. He informs Wolfram that his repentance has been rejected by the pope, who declares he can no more receive forgiveness than can the pope's staff deck grow green leaves; in despair, Heinrich seeks to return to Venus, who appears, to Wolfram's horror. Wolfram urges Heinrich to reject her and seek salvation in vain, until he names Elisabeth as Heinrich's angel, praying for him at the throne of God. Venus vanishes. The nobles descend from the Wartburg, bearing Elisabeth's bier, on which the redeemed Heinrich sinks insensible. The younger pilgrims return, bearing the staff which has burst into new leaf, and all join to acclaim the miracle of God's mercy.