Prepare the chickpeas and tuna. Drain and rinse the chickpeas thoroughly under cold water, then allow them to drain well. Drain the canned tuna and use a fork to gently break it into small flakes.

Place the chickpeas and tuna into a large mixing bowl. Add the finely chopped celery, diced bell pepper, and chopped parsley. Toss the ingredients lightly so the vegetables distribute evenly throughout the mixture.

In a separate small bowl or jar, whisk together the olive oil, lemon juice, salt, and black pepper. Mix until the dressing becomes smooth and slightly emulsified.

Pour the lemon dressing over the tuna and chickpea mixture. Toss gently until everything is evenly coated. For the best flavor, chill the salad for about 30 minutes before serving, though it can also be enjoyed immediately.