Spritz the bottom of large pot with olive oil spray and saute onion and garlic over medium heat until onion is softened and translucent.

Add water, chicken broth, carrots, bok choy, and broccolini; bring to a boil. Reduce heat and simmer until vegetables are slightly tender, about 10 minutes. Add chicken; continue simmering until chicken is no longer pink in the center, about 10 minutes.