Cook the pasta according to the package instructions until it's al dente. Drain and set aside.
In a large skillet, brown the ground beef over medium-high heat until it's no longer pink. Drain any excess grease.
Add the diced onion to the skillet with the cooked beef. Sauté until the onion becomes translucent.
Sprinkle the taco seasoning over the beef and onion mixture. Stir to evenly coat the meat with the seasoning.
Pour in the diced tomatoes (with their juices) and tomato sauce. Stir everything together and let it simmer for a few minutes
Add the cooked pasta to the skillet with the beef and sauce. Gently stir to combine all the ingredients.