Heat 1 tablespoon of olive oil in a large skillet over medium-high heat until shimmering.
Add the turkey sausage, break it up with a spoon, and cook for 5–7 minutes until browned and registers 165°F internally.
Transfer the cooked sausage to a plate, leaving the drippings in the skillet.
Add the remaining 1 tablespoon of olive oil, then add the chopped onion and bell peppers; sauté for 7–10 minutes until tender-crisp.
Stir in the minced garlic and Italian seasoning; cook for 1 minute until fragrant.
Pour in the undrained diced tomatoes, stir to combine, and bring to a gentle simmer.
Return the turkey sausage to the skillet, stir well, and season with salt and black pepper.
Reduce heat to medium-low, cover, and simmer for 5–7 minutes to meld flavors.
Taste and adjust seasoning if needed, then serve hot over rice, pasta, or on its own.