Heat olive oil in a large non-stick skillet over medium heat.
Add the chopped onion and cook for 3 minutes until softened.
Add the minced garlic and cook for 1 minute until fragrant.
Add the chicken pieces to the skillet and season with salt, black pepper, and dried oregano.
Cook the chicken for 5-7 minutes, stirring occasionally, until cooked through and lightly browned.
Add the diced zucchini and cherry tomatoes to the skillet and cook for 3 minutes until slightly softened.
Pour in the chicken broth and bring the mixture to a boil.
Add the orzo pasta to the boiling broth, reduce heat to medium-low, and simmer uncovered for 8-10 minutes, stirring occasionally, until the orzo is tender and the broth is mostly absorbed.
Remove the skillet from heat and stir in the fresh lemon juice and chopped parsley.
Adjust seasoning with additional salt and black pepper if needed.
Serve warm.