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.

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

Romeo confesses his new love for Juliet to Friar Laurence, who is ecstatic at the opportunity to potentially end the feud. He assures Romeo that he will marry the two, but only if Romeo proves to be more dedicated to Juliet than he was to Rosaline.

Later 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 his life away to the law. Tybalt flees Verona a wanted murderer. The Capulets swear an everlasting grudge against Romeo for his role in sparking the quarrel.

Upon hearing the news, Juliet weeps for the loss of her cousin and Romeo's new status as her family's sworn enemy. She soon learns that her father wishes to marry her off to the County Paris to cheer her up. Horrified, she tells him that she cannot marry Paris as she loves another man. Her surprised father requests to know who this new suitor is so that he may evaluate his worth, but she refuses to reveal 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 insists that unless she names this mystery suitor, she will marry Paris by default. When Romeo comes to visit that night, she asks him to meet her at Friar Laurence's the next day to ask for counsel.

In the morning, Romeo, Juliet and Friar Laurence seek a way to make the feuding families see the light and to break the news of their love. 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 have mysteriously gone missing. The Nurse feigns surprise. Montague and Capulet accuse each other of kidnapping their respective children while everyone remarks how odd it is that these two individuals have 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 that the feud has ended. Later, they encounter the runaway Tybalt in the street, who tries to kill Romeo. Juliet stands up for Romeo, outing herself as his wife, whereupon a furious Tybalt strikes her in the face. The couple barely escapes with their lives, with the help of Balthasar and passersby.

When the letter is delivered to Montague and Capulet by 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 as they recognise the writing as Romeo's own. However, they decide to conceal the matter from their relatives.

Meanwhile, Friar Laurence 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 learned to his relatives: Romeo and Juliet have married and run away to Mantua. The news causes an outrage in the house of Capulet and the Montagues are equally livid when they learn it from the Capulets. Romeo and Juliet's parents are overwhelmed to realise 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 Laurence 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, 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 their families, they now surrender themselves to be punished.

The Prince intervenes and tells both families that all have been punished for what they've done: Montague and Capulet have lost their own children to each other 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 on the spot, 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 Laurence assures 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, 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."