Bring a large pot of salted water to a rolling boil. Add the spiral rotini pasta and cook according to the package instructions until al dente, about 8–10 minutes.

Drain the pasta using a colander and rinse under cold running water for 1–2 minutes to cool it down and remove excess starch.

Chop the vegetables: slice the cherry tomatoes in half, finely dice the red onion, and slice the black olives. Cut mozzarella balls in half.

In a large mixing bowl, combine the cooled pasta, chopped vegetables, and mozzarella. Gently fold to mix.

Drizzle Italian dressing over the pasta salad mixture and toss gently to coat.

Transfer the salad to the refrigerator for at least 30 minutes before serving to let flavors meld.