She is voiced by Alyson Stoner.
Isabella worked with the other Fireside girls to rescue the gang after they'd been captured. She was quick and resourceful in freeing them and afterward continued to evade capture as she retrieved the suit they'd made.
Isabella is a young girl with a tiny nose, deep blue eyes, and long, straight black hair with short bangs.
During the invasion, Isabella wore a white tank top and baggy grey pants tucked into a pair of heavy black boots with white soles. She wore a bright purple belt with a large oval belt buckle over her pants, and a matching strap slung over her shoulder. There is a grey pocket hanging from the strap.
Her trademark pink bow rests on the side of her head, with the ribbon worn as a headband. Finally, she has a pair of matching fingerless gloves with long cuffs.
She is the leader of Danville's local Fireside Girls troop. She has a huge crush on her neighbor, Phineas Flynn, and is always willing to help him and his stepbrother Ferb Fletcher with their daily activities.
In "The Phineas and Ferb Effect", Isabella appeared alongside the other Fireside girls just on time to save the gang after they'd been captured by Pistachions. Afterward, she retrieved their Murphy's Law Suit but was eventually turned into a Pistachion until Derek was finally defeated.
“Whatcha doin'... all tied up like this?”
- Isabella is the only main character from Phineas and Ferb to not play a major role in the crossover or be seen wearing her signature outfit.