In 12-inch skillet, heat oil over medium-high heat until hot. Add chicken and garlic; cook and stir 3 minutes. Add carrots and onion; cover and cook 2 to 3 minutes or until vegetables are crisp-tender, stirring once.
Stir in all remaining ingredients except spinach. Heat to boiling. Reduce heat; cover and simmer 12 to 15 minutes, stirring occasionally, until most of liquid is absorbed and orzo is tender.
Stir in spinach; cover and cook 2 to 3 minutes longer or until spinach is wilted.