Heat the olive oil in a large pot over medium heat. Add the onion, carrots, and celery and cook for 5 minutes until the vegetables begin to soften.
Stir in the garlic and cook for 1 minute until fragrant.
Pour in the homemade chicken broth and add the chicken breasts. Bring to a simmer and cook for 15 minutes until the chicken is fully cooked.
Remove the chicken from the pot, shred it with two forks, and set it aside.
Add the orzo to the simmering broth and cook for 8 minutes until tender.
Return the shredded chicken to the pot. Stir in the lemon zest, lemon juice, parsley, and dill. Season with salt and pepper and serve.