Heat olive oil in a saucepan over medium heat; cook and stir onion in the hot oil until softened, 5 to 10 minutes.
Add salsa and water to onion and bring to a boil.
Reduce heat and simmer; add chicken, black beans, and chili powder and return to a simmer.
Cover saucepan and simmer chili until chicken is heated through, about 10 minutes.
