When Jessie is introduced, she tackles Woody with excitement at the prospect of finally meeting a Woody doll. She is happy that she and the other toys are finally going to come out of storage and go to the toy museum in Japan that they are destined for.
It is Jessie who introduced Woody to the facts about the character on which he is based. She shows him a large array of merchandise based on "Woody's Roundup" and Stinky Pete explains how the show was canceled after the launch of Sputnik and the resulting interest in the Space Race and science fiction, diminishing the popularity of westerns.
When Woody indicates that he has no intention of going to Japan, she becomes bitter, and Woody comes to suspect her of attempting to sabotage his escape, including waking Al to prevent Woody from recovering his damaged arm. After Woody is fixed, he learns Jessie's tragic back story about her previous owner. Emily, a young girl who owned Jessie had loved her just like Andy loves Woody, but as she grew older found more 'grown-up things' like make-up to play with, forgetting all about Jessie. Years later, Emily found Jessie under the bed and spent one last day with her on a car trip, only to place her in a charity box. Woody, realizing he could easily suffer the same fate with Andy, then chooses to stay, which Jessie finds absolutely thrilling, especially when he begins to anticipate his journey to Japan in excitement.
Ultimately, it is Stinky Pete that is revealed as the attempted saboteur when Woody finally decides to take Jessie and Bullseye with him back to Andy's room. Because of Stinky Pete's sabotage, Al packs the roundup gang into the case and heads for the airport. There, Buzz Lightyear and the toys free Woody and gets rid of the vile Stinky Pete, but Jessie still remains trapped as the case gets loaded into the luggage transporter, while Bullseye manages to escape in time. Buzz and Woody mount Bullseye and chase after the luggage transporter, which Woody climbs onto. Woody follows the case into the plane's cargo hold and frees Jessie from inside. When Woody offers take Jessie home, she is rather uncertain at first, but eagerly accepts when she learns from Woody that Andy has a baby sister named Molly. However, the two toys become trapped in the cargo hold, but Woody locates another escape hatch. Using his pull-string, Woody and Jessie swing down from the plane and land on Bullseye right behind Buzz just before the plane takes off. At the very end of the film, when Andy returns from camp after the toys return home, he is pleased to have the new toys added into his collection, calling Jessie "Bazooka Jane", and Buzz seem to have hold a romantic interest in her, complimenting for her hair. Touched by this comment, Jessie, in return, describes Buzz as "the sweetest space toy she has ever met". Shortly after, she and Buzz are seen together with Woody and Bo Peep as they watch Wheezy sing "You've Got a Friend in Me."
In Toy Story 3, Jessie continues to have a romantic relationship with Buzz. She decides that the toys should take control of their own fate when Andy seemingly throws them away. At Sunnyside Daycare, Jessie argues that Andy doesn't care for them anymore when Woody tries to explain he really didn't mean to. When the toys are played with, they are tortured by the innocent children at the daycare. After Mrs. Potato Head learns Andy really meant to keep them, the toys confront Lotso, the leader of Sunnyside, on the matter of both the children and leaving the daycare. Lotso resets Buzz to his 'Space Ranger' persona, who captures the toys and acts as their prison guard. When Woody returns, the toys escape, and reset Buzz again, but this time to a Spanish speaking version of his Space Ranger self. She is initially uncomfortable with Buzz, but falls for him all over again when Buzz saves her from a falling TV in a garbage truck; this ultimately resets Buzz to his normal self. The toys are dumped at a landfill, and are about to be killed in an incinerator, until the aliens rescue them from certain death. They return home, but Andy gives them to Bonnie, a little girl who took Woody home at one point before. In the credits, Jessie uses Buzz's Spanish side to dance with him to "Hay Un Amigo En Mi."