In a large skillet or Dutch oven, heat olive oil over medium-high heat.
Add ground beef and cook until browned, about 6–7 minutes, breaking it apart as it cooks. Drain excess fat if needed.
Stir in onion, bell pepper, celery, and garlic. Cook until vegetables are softened, about 5 minutes.
Add uncooked rice, Cajun seasoning, smoked paprika, thyme, black pepper, and cayenne. Stir to coat rice with seasonings.
Pour in beef broth, bring to a boil, then reduce heat to low. Cover and simmer for 20 minutes, or until rice is tender and liquid is absorbed.
Remove from heat and let sit covered for 5 minutes. Fluff with a fork.
Garnish with sliced green onions and parsley before serving.