Bring a large pot of salted water to a boil and cook the rice according to package directions.
While the rice is cooking, peel and cut the carrots in half lengthwise, then slice into thin strips. Halve the cherry tomatoes and artichokes, cube the mozzarella, chop the sun-dried tomatoes, and combine all ingredients in a large bowl.
Drain the cooked rice and rinse under cold running water to cool and remove excess starch. Add the cooled rice to the other ingredients.
Drizzle with olive oil, season with salt and pepper, and mix gently. Add the well-drained, flaked tuna and fold in carefully.
For extra flavor, serve with a little mayonnaise on the side.