Alya is brown-skinned and at a medium height with hazel eyes. She has dark reddish-brown wavy hair that goes to her shoulders, with the tips of her hair having a lighter shade of copper red. Above her right eyebrow, she has a beauty mark.
She wears black-rimmed glasses with a white spot on each side, whereas her outfit consists of a white tank top underneath a plaid shirt with white, orange, and purple stripes; light blue jeans, and white sneakers with black tops.
Alya is a rather energetic and passionate yet down to earth and smart girl. She is extremely loyal, supportive, and helpful, like going out of her way to encourage and (sometimes literally) push Marinette into spending time with Adrien. Her cleverness and foresight have come in handy many times. After Marinette thinks she accidentally lost a video of Ladybug on Alya's cellphone, Alya explains that she had already posted the video on her blog, expecting something to go wrong when she showed Marinette the video. From thoroughly observing Ladybug and Cat Noir while in action, Alya has figured out the basics of the superhero's work, like breaking the akumatized object to stop the villain. She doesn't like being undermined or doubted by others, especially when it comes to her work.
Alya has a dramatic side to her personality as well, such as when she pretends to be a unicorn with Manon (in Stormy Weather) and when she makes an excuse to Adrien's photographer, who asks for her to be a support model for Adrien, so Marinette can do the modelling instead. Having to babysit her several younger siblings at home, she is great with kids. When it comes of anything involving Ladybug and Cat Noir, Alya easily becomes very excited and basically has a single goal of updating her blog as soon as possible, like when she is kidnapped by the Pharaoh to be a sacrifice yet still records herself and livestreams the video on her blog in "The Pharaoh". She also tends to jump to conclusions, such as when she quickly suspects Chloé of being Ladybug after seeing the mayor's daughter with a Ladybug prop yo-yo and suit and mistaking them for the real ones. She is intent on finding out who the civilian identities of the two superheroes are, and is willing to follow almost any lead she is given towards that goal. In her pursuit for the truth Alya tends to forget her own safety at times, needing rescue from the very superheroes she's filming. Sometimes, she goes too far, like spying on Chloé's locker, which results in her getting punished by Mr. Damocles.