*Jessie has magenta long hair that she wears curled in a comet-tail behind her head. She typically wears a pair of large green orb earrings that have become a staple signature part of her look and is never seen without them, even in disguise.

Jessie is the short-tempered member of the Team Rocket trio, having a tough streak as well as being vain and very prone to anger. Every time she has stolen someone else's belongings or Pokémon, she always claims, "Your things are mine, my things are still mine." Due to her pride, she usually underestimates her opponents' strength, which is a cause for her own failure.

She tends to be a drama queen and has a diabolical temperament.

She also values her beauty and long hair; she will become furious if her face or her hair is damaged. A prime example is in Tracey Gets Bugged when a younger Scyther manages to slash her hair down to a shoulder-length, devastating her and sending her into a rage. Jessie also shows her violent outrage when someone insults her beauty by calling her old. Her anger also scares James and Meowth, especially when their missions end up in a failure.

Jessie is shown to care about her Pokémon despite her nasty temperament.

Jessie has an affinity for snake-like Pokémon such as her Ekans who later evolved into Arbok and her Seviper. She also makes has a love of Poison-type Pokémon as seen in The Ninja Poke-Showdown!. In addition, she adored her Dustox, which she released in Crossing Paths!. Dratini and Smoochum are her favorite Pokémon too, so she'll try to steal any one of them if she sees one.

Jessie also has a long-standing rivalry with Cassidy, another member of Team Rocket. Their rivalry is most pronounced in some episodes involving Cassidy and Butch, much like Ash's rivalry with Gary Oak. The episode Grating Spaces!, reveals that Jessie and James aren't allowed the same privileges as other Team Rocket members, thanks to their previous blunders. This means that they aren't given vacation days or extra Pokémon to assist them on missions.

During the events in Pokémon: Black & White, Jessie's tough personality subsides due to her promotion to an Advanced Agent. She became more calm and collected, much more relaxed, and more like a true villain but maintains her mean streak when facing Ash and his friends. But after Operation Tempest is thwarted by Ash and the group she returns to her old personality.

In the XY series, Jessie is shown to be capable of showing love. As seen in one episode when she and her Wobbuffet were saved by Dr. White and his female Wobbuffet from drowning into a river, she falls in love with him, going so far as to work as his assistant in her Jessilia disguise. However, she dislikes rejection and shortly returned to James and Meowth after finding out that Dr. White liked someone else. She later throws away the bouquet of white flowers that she was planning on giving to Dr. White. This trait is also shown when she saw Steven Stone's photo in Sawyer's notebook and became love-struck upon seeing Steven himself.

Jessie also loves popularity when she aspires to become a Kalos Queen and became popular with many people.

In Mimikyu Unmasked!, Jessie can be a shopaholic and spent all of her team's money at a shopping mall. She also has a talent for sewing and used her skill to fix Mimikyu's costume.

Although she is shown to be very mean to her own Pokémon such as punching or shouting rudely at them, she does care for them. For example, she along with James and Meowth helped Arbok to escape with Weezing, and a group of Koffing and the Ekans, by taking hits from Rico's Pokémon. She also let Dustox follow her true love by smashing Dustox's Poké Ball.

Jessie becomes less selfish and less harsh towards her teammates: James & Meowth as the series progresses. In 'Pokémon Journeys,' it is demonstrated several times that Jessie is a coach of 'self-confidence' for her teammates.*