Place chicken broth in a large stockpot over medium-high heat and bring to a simmer.
Add carrots, celery, onion, 1 teaspoon salt, thyme and pepper, stirring to combine. Return broth to a simmer. Reduce heat to medium-low, cover pot and simmer until vegetables are tender, about 20 minutes.
Bring a medium saucepan of heavily salted water to boil over high heat. Add noodles and cook according to package directions until al dente. Drain in a colander.
When vegetables are tender, add cooked chicken and drained noodles to the stockpot, stirring to combine. Return soup to a simmer and cook until flavors meld, about 5 minutes. Taste and season with salt and pepper, as desired.