Rinse the rice under cold water until the water runs clear. Set aside.
In a large skillet or saucepan, heat the vegetable oil over medium heat. Add the diced onion and green bell pepper; sauté for about 5 minutes until softened.
Stir in the minced garlic and sliced sausage. Cook for another 5 minutes until the sausage is browned.
Add the rinsed rice to the skillet, stirring to combine with the sausage and vegetables.
Pour the chicken broth into the skillet, then add the Cajun seasoning, dried thyme, black pepper, and salt. Stir well to combine.
Bring the mixture to a boil, then reduce the heat to low. Cover and simmer for about 15-20 minutes, or until the rice is tender and has absorbed the liquid.
In the last 5 minutes of cooking, gently fold in the shrimp, cover, and continue cooking until the shrimp turn pink and are cooked through.
Once cooked, remove from heat and let the dirty rice sit, covered, for an additional 5 minutes. Fluff the rice with a fork and garnish with chopped green onions before serving.
For added spice, consider adding diced jalapeños or a pinch of cayenne pepper.
Leftovers can be stored in an airtight container in the refrigerator for up to 3 days. Reheat gently in a skillet with a splash of broth.