Nine years prior to the current events, amidst the gap between the second and third films, R.C. finds himself swept away by a storm drain as Andy forgets to bring him back inside. In a valiant effort, Woody and the rest of the toys successfully rescue him. However, during their frantic endeavors, a visitor, a friend of Andy's mother, purchases Bo Peep along with her lamp. Despite Woody's desperate attempts to stop the sale, Bo reassures him, conveying that it is an inherent part of a toy's life to eventually be taken away.
Fast forward two years after Andy has graciously donated his toys to Bonnie, and Woody finds contentment amongst the familiar faces of the toy family. Concerned that Bonnie might feel anxious during her kindergarten orientation, Woody, who feels neglected, sneaks into her backpack with the intent of offering support. His worries soon materialize when a boy bullies Bonnie, prompting Woody to discreetly assemble a spork and other discarded items on her table. Bonnie transforms these into a handmade creation she affectionately names "Forky." To Woody's shock, Forky comes to life, believing he was crafted from trash rather than designed to be a toy.
In a chaotic road trip with Bonnie's family, Forky's continued belief as 'trash' leads him to leap out of the moving vehicle. Woody pursues him, working hard to instill in Forky the joy that comes with being a beloved toy. Their adventure leads them to an RV park in a neighboring town where Bonnie and her family have made camp. Upon arriving, Woody is elated to spot Bo's lamp in an antique shop. Upon his quest to locate Bo, he and Forky encounter the doll Gabby Gabby and her devoted ventriloquist puppets, the Bensons. Gabby initially offers to reunite them with Bo, but soon unveils her ulterior motive—stealing Woody's voice box since her own is broken and she's been passed over by children.
As the two struggle to escape, Forky becomes the Bensons' captive. After releasing himself from the shop, Woody realizes the grave mistake of abandoning Forky. His search leads him to reunite with Bo, who has embraced a nomadic life dedicated to guiding lost toys toward new owners. Bo, along with her little friend Giggle McDimples, devises a plan to rescue Forky from the antique shop via an exhilarating carnival route.
Meanwhile, Buzz takes it upon himself to find Woody, relying on his unique button-activated phrases for guidance. After a series of misadventures—including a narrow escape from a carnival game—Buzz finally reunites with Woody and Bo. They enlist the help of Ducky and Bunny to orchestrate a rescue plan for Forky, promising them companionship as Bonnie's toys alongside Duke Caboom, a flamboyant Canadian stuntman toy.
When their rescue plan at the antique store takes a turn for the worst, Woody ends up in a heated argument with the other toys, indirectly hurting Bo's feelings. As Bo, Duke, Giggle, Ducky, and Bunny head back to the carnival, Woody makes the difficult choice to give his voice box to Gabby Gabby in exchange for Forky's freedom. Gabby Gabby, initially desperate to be chosen by a little girl named Harmony, finds herself rejected yet once again, leading to an emotional moment where she offers Woody back his voice box, which Woody firmly declines, insisting she keep it.
After Bonnie returns for her forgotten backpack, the toys follow them back home. With Duke's motorcycle prowess, Buzz and Forky successfully reunite with Bonnie. Taking Woody's advice, Gabby Gabby empathetically comforts a lost girl and finally finds her own family. As Ducky, Bunny, Giggle, and Duke bid farewell to Woody, he faces a significant decision.
As he stands with Bo, a pang of uncertainty washes over him regarding returning to Bonnie. Gaining confidence from Buzz, Woody makes the life-altering decision to remain with Bo and assist lost toys in their journeys. In a heartfelt farewell, Buzz and the group hug Woody, forever changing the dynamics of their relationships. As Bonnie’s RV departs, Woody and Buzz share their iconic farewell, > "To infinity...and beyond." Under the vibrant night sky, Woody and Bo enjoy their newfound lives together.
In a brief narrative fast-forward, one year later, kids watch Ducky and Bunny put on a comedic act at a new pier. Back in Bonnie's room, reminiscent of when Woody introduced Forky, Jessie brings home a new creation: Karen Beverly, a decorated plastic knife. Forky, enchanted, commits to guiding her journey through life as a toy, but when she asks, "How am I alive?" he finds himself at a loss for words and simply responds, "I don't know."
In a playful post-credits scene, Duke Caboom impressively jumps onto the Pixar logo's 'I', strikes a pose, and shares a long-awaited high five with Combat Carl, providing a delightful conclusion to this memorable tale.
