Bring a large pot of lightly salted water to a boil. Cook orzo in the boiling water, stirring occasionally until tender yet firm to the bite, about 11 minutes. Drain and rinse under cold running water.
Combine orzo, tomato, onion, bell pepper, celery, lemon-pepper seasoning, and salad dressing in a large bowl; mix well. Refrigerate for 1 hour. Mix in Parmesan cheese. Refrigerate for 2 more hours or overnight.