Act I
In July 1899, a group of orphaned and homeless newsboys live in a Lower Manhattan lodging house with their informal leader, seventeen-year-old Jack Kelly. In the early hours of the morning, Jack tells his best friend, Crutchie, of his dream to one day leave New York for a better life out West ("Santa Fe (Prologue)"). As the sun rises, the rest of the newsies awaken and prepare for a day on the job, finding as much joy as they can in their life of poverty ("Carrying the Banner"). At the circulation gate, Jack meets a new newsboy named Davey and his nine-year-old brother Les. Unlike the other newsies, the brothers have a home and a loving family, and have been pulled out of school only temporarily to support their parents while their father is out of work with an injury. Seeing young Les as an opportunity to sell more papers, Jack offers to be their partner. Meanwhile, the publisher of the New York World, Joseph Pulitzer, expresses his displeasure at his newspaper's declining circulation. To increase his profits, he decides to increase the cost of the papers for the newsies, ignoring his secretary's concerns that "it's going to be awfully rough on those children" ("The Bottom Line").

Later, Jack, Davey, and Les are selling their final newspapers of the day when the corrupt Warden Snyder of the Refuge, a juvenile detention center, recognizes Jack as an escapee from his institution. He attempts to chase the boys down, but they find cover in a vaudeville-style theatre owned by Jack's friend Medda Larkin, whom he regularly paints backdrops for. As Medda performs ("That's Rich"), Jack spots a young female reporter named Katherine Plumber. She rebuffs Jack's attempts to flirt with her, but she is then charmed when he leaves her with a sketch of her portrait ("Don’t Come A-Knocking/I Never Planned on You").

The next morning, the newsies discover that the cost of newspapers has been raised to sixty cents per hundred. Outraged, Jack declares the newsies to be a union and organizes a protest ("The World Will Know"). Katherine decides to cover the strike, seeing it as an opportunity to be taken more seriously as a journalist ("Watch What Happens"). The next day, the boys have informed the rest of the city's newsies about the strike, but each neighborhood claims that they will only join once Spot Conlon, leader of the Brooklyn newsies, gives the okay. The newsies are discouraged by the lack of support, but Davey convinces them to protest regardless of who shows ("Seize the Day"). Scabs arrive to take the newsies' jobs, but are persuaded to join the strike by Jack, who delivers an impassioned speech condemning child labor and the city's treatment of the poor. The protest appears to be headed for success, but is soon cut short when Pulitzer's goon squad and the police arrive to break it up by force. During the ensuing fight, Crutchie is apprehended, badly beaten, and taken to the Refuge. A devastated Jack escapes to the lodging house rooftop and, blaming himself for the protest's failure, fantasizes about running away forever ("Santa Fe").

Act II
The next morning, Katherine finds the battered and bruised newsies in Jacobi's Deli, only to learn that no one knows where Jack is as rumors circulate about his whereabouts. She cheers the other newsies up by showing them that her article about the strike made the front page of the New York Sun. Thrilled, the boys rejoice at making the headline and imagine what it would be like to be famous ("King of New York"). However, Pulitzer has declared a blackout on strike news, meaning Katherine's story will be the only one to run. Meanwhile, Crutchie writes a letter to Jack, describing the filthy and abusive conditions at the Refuge. He asks Jack to make sure the newsies continue to look out for one another, signing the letter, "your brother, Crutchie" ("Letter from the Refuge"). Later, Davey finds Jack hiding out in the basement of Medda's theatre and informs him of his plan to hold a citywide rally in the theatre. Jack, distraught over Crutchie's arrest, refuses to put the other boys back in danger, but Davey, along with Katherine and Les, convinces him that their fight is too important to quit ("Watch What Happens (Reprise)").

Back at the World, an angry Pulitzer plots with Warden Snyder about how to stop Jack. Snyder reveals that Jack was originally sentenced to the Refuge for vagrancy, but has since become a "frequent visitor," with his most recent arrest being for trafficking stolen food and clothing. Jack soon arrives with an invitation for Pulitzer to attend the rally Davey has planned. Pulitzer declines, assuring Jack that no newspaper will violate the blackout order by covering the rally. Pulitzer claims that if it's not in the papers, it never happened. Jack attempts to counter by claiming the newsies already have a reporter on their side, but Pulitzer reveals that Katherine is his daughter and that "Plumber" is only her pen name. He offers Jack a choice: if the strike is called off, Jack will be cleared of all charges and given enough money to leave for Santa Fe, but if not, he and the other newsies will all be arrested and sent to the Refuge ("The Bottom Line (Reprise)"). Katherine, who has been listening in secret, attempts to apologize to Jack, but he brushes her off as he is detained by Pulitzer's goons and led into the cellar.

The next morning, Spot Conlon and the Brooklyn newsies declare their support of the strike and head to the rally ("Brooklyn's Here"). Jack, believing there is no way the newsies can win against Pulitzer's money, power, and connections, shows up to the rally to reluctantly suggest the strike be called off. He accepts the Santa Fe money from one of Pulitzer's men as Davey, Spot, and the other newsies watch in disbelief, calling him a traitor and a scab. Jack flees to his rooftop, only to find that Katherine has beaten him there. She has discovered Jack's drawings of the abuse he suffered at the Refuge among his belongings and realizes that he stole to feed and clothe the other boys. They argue about their respective betrayals and the fate of the strike, but the argument is cut short when she impulsively kisses him. Katherine has a new idea: use Jack's drawings and one of her articles to print their own newspaper, calling for every worker under 21 to strike alongside the newsies. Jack agrees, recalling an abandoned printing press in Pulitzer's cellar, but before getting to work, they share a romantic moment, each stating that the other has given them "something to believe in" ("Something to Believe In").

The other newsies join Jack and Katherine in printing their own paper, the Newsies Banner, and distribute copies throughout the city ("Once and for All"). A copy reaches Governor Theodore Roosevelt, who arrives in full support of the newsies' cause. Roosevelt gives Pulitzer an ultimatum, forcing the latter to concede to Jack's demands. Jack proposes that Pulitzer buy back every paper the newsies fail to sell each day. Initially reluctant, Pulitzer agrees when Jack points out he will still ultimately benefit from the increased sales. Jack and Roosevelt inform the newsies that the strike is over and they have won. As the newsies celebrate, Roosevelt informs them that he has shut down the Refuge, citing Jack's drawings as his motivation to do so. Crutchie returns to his friends, and Snyder is arrested. Impressed at the influence Jack's drawings had on the governor, Pulitzer offers him a job as a daily political cartoonist. Jack declines, claiming it is time he leaves for Santa Fe, but Davey, Katherine, and Crutchie remind him that "New York's got us, and we're your family." Ultimately, Jack decides to stay and chooses to remain a newsboy as well as accept the cartoonist job ("Finale").