Bring a large pot of salted water to a rolling boil. Add the tortellini and cook according to package instructions, typically about 3-5 minutes, until al dente. Drain and rinse under cold water.

While the tortellini cools, prepare the vegetables: halve the cherry tomatoes, dice the red onion, and chop the fresh basil leaves. Set aside in a large bowl.

In a mixing bowl, gently combine the cooled tortellini, halved cherry tomatoes, diced red onions, and mozzarella balls.

Drizzle the basil pesto and olive oil over the salad mixture. Toss gently until everything is coated.

Season with salt and black pepper, tossing to combine the flavors evenly.

Cover the salad bowl with plastic wrap or transfer it to an airtight container. Chill in the refrigerator for at least 30 minutes to allow flavors to meld.