Bring a large pot of salted water to a boil and cook rigatoni according to package directions until al dente.

While pasta cooks, heat olive oil in a large skillet or Dutch oven over medium-high heat.

Add diced onion and sauté for 3 minutes until translucent, then add minced garlic and cook for 1 additional minute.

Add ground beef to the skillet, breaking it apart with a spatula, and cook until fully browned; drain excess fat.

Stir in marinara sauce, Italian seasoning, salt, and pepper; reduce heat to low and simmer for 5 minutes.

Add cubed Velveeta cheese to the sauce and stir continuously until the cheese is completely melted and incorporated.

Drain the pasta and add it directly to the skillet, tossing thoroughly to coat the rigatoni in the creamy sauce.

Serve immediately while hot.