Romeo goes to the party to meet Rosaline, but falls for Juliet instead. He resolves to end his unrequited love for Rosaline and pursue the responsive Juliet instead.

Romeo and Juliet meet on the balcony, confess their love for one another, and seek a way to get married.

Romeo confesses his new love for Juliet to Friar Lawrence, who is ecstatic at the opportunity to potentially end the feud. He assures Romeo he will find a way to marry the two, but not immediately. He asks Romeo to keep in close contact with him.

When the nurse comes, Romeo relates Friar Lawrence's words to her, and tells Juliet to be patient for her wedding day. In the meantime, he will come to visit her every night.

That day, Tybalt kills Mercutio. Benvolio forcibly restrains Romeo from fighting Tybalt, urging him to use the Prince's sword instead of his own, and not to throw away his life and freedom to the law. Tybalt flees Verona a wanted murderer. The Capulets swear an everlasting grudge against Romeo, because he was the cause of the violence, and because he, with Benvolio, had borne witness against Tybalt.

Juliet weeps for Tybalt, and because Romeo has become her family's sworn enemy. She learns that her father wishes to marry her off to the County Paris to cheer her up. She tries to tell him that she cannot marry Paris as she loves another man. Her father requests to know who this new suitor is so he may evaluate his worth, but she tells him she cannot divulge his identity. She tells him only that he is no less worthy than Paris, and comes from a good family. Capulet is confused and angry at Juliet's obfuscation and obstinacy, and insists that unless she names this mystery suitor, she will marry Paris by default. Shortly thereafter, when Romeo comes to visit, she asks him to meet her at Friar Lawrence's the next day to ask for counsel.

The next day, Romeo, Juliet and Friar Lawrence search for a way to make the feuding families see the light, and also to break the news of their love to their families. The friar reasons that people repent only in time of distress, so he suggests that the two of them vanish from the city and spark a mutual crisis in the houses of Montague and Capulet. He will send them away to Mantua that night, but before that he will marry them! The two young lovers are ecstatic. That night, Romeo helps Juliet escape her house using the rope ladder the nurse brought, and they rush to the church. The friar performs the ceremony and sends the newlyweds on their way, with Friar John as escort. On their first night in Mantua, they consummate their marriage and sleep peacefully together for the first time.

In the morning, all Verona is in consternation when it is discovered that Romeo and Juliet are both missing from their beds. No letter is found left behind, adding to the confusion. The Nurse acts surprised. Montague and Capulet accuse each other of kidnapping their respective children. Everyone remarks how odd it is that these two individuals have both disappeared at the same time.

Back in Mantua, as instructed by the friar, Romeo and Juliet write a joint letter to their parents, explaining what they have done, imploring their forgiveness, and promising to return once they receive news from Balthasar that the feud has ended. They did not have time to write this letter before they left. Later, they encounter the runaway Tybalt in the street, who tries to kill Romeo. Juliet stands up for Romeo, outing herself as Romeo's wife, and an a furious Tybalt strikes her in the face for her treachery to the house of Capulet. Romeo and Juliet barely escape with their lives, with the help of Balthasar and passersby.

When the letter is delivered to Montague and Capulet by the hand of Balthasar, they refuse to believe it. Capulet calls it a forgery, a cruel trick played on him in his old age, and destroys his copy. Montague and his wife are more in denial, because they recognise the writing as Romeo's own. However, they decide to hush the whole matter up and inform no one of it.

Friar Lawrence and Juliet's nurse privately confess their scheme to the Prince, who expresses surprise at these new developments and places tentative hope in their plan.

Tybalt hurries back to Verona in disguise and discloses what he has independently learned to his relatives: Romeo and Juliet have married and have run away to Mantua. This not only confirms the letter's authenticity but also gives away the lovers' whereabouts. Tybalt's news causes an outrage in the house of Capulet, and the Montagues are equally livid when they learn this fact from the Capulets. Romeo and Juliet's parents are overwhelmed by the realisation that the letter told the truth. Capulet, in anguished hindsight, finally puts all the pieces together: Romeo's presence at the party, Juliet's description of her lover, and her refusal to identify him by name. County Paris mourns for the loss of his bride and curses Romeo for stealing her away.

Fighting breaks out in the street once more, more violent than ever. Friar Lawrence urgently sends for Romeo and Juliet to return.

The two lovers come back disguised as monks. Their families are gathered in the town square, accusing one another before the Prince.

In the midst of the chaos, Romeo and Juliet reveal themselves and, bowing down to the ground, beg the forgiveness of both families. They give a speech on how their marriage would have been acceptable if it weren't for the feud. Nevertheless, to clear the shame they've brought to their families, they now surrender themselves to be punished.

The Prince intervenes and tells the two families that all have been punished according to what they've done so far: Montague and Capulet have lost their own children to each other because of love, and the feud has now also cost Mercutio, the Prince's kinsman, his life. He orders them to end the feud that very day, seeing that they are all relatives now by marriage. Unwilling to harm or disown their beloved children, Lords Montague and Capulet make peace right there for the sake of peace, with Capulet calling Montague his brother and Montague accepting Juliet as his own daughter.

Romeo also implores the heartbroken County Paris for forgiveness for stealing his intended bride. The magnanimous County dismisses the matter, saying that heaven has overruled everyone's best intentions in order to bring peace to Verona, and with that, he is content. Friar Lawrence intervenes and reassures Paris that Juliet is not the only girl in the world. Citing Romeo's experience with Rosaline, he expresses hope that Paris too will quickly find a maid who makes him forget even Juliet.

With the feud over, the now-united families hold a joint wedding feast to celebrate their children's return and marriage. As a gesture of mercy, and because the feud is now over, the Prince pardons Tybalt for the death of Mercutio and orders that he be informed of it, but Tybalt is never seen or heard from again.

The play concludes with the observation that

"For ne'er a wedding did more joy beget;

Than this of Romeo and his Juliet."