Coat the interior of the slow cooker using nonstick cooking spray.
In a skillet over medium heat, brown the ground beef until no longer pink; discard any excess fat.
Following the package directions, incorporate the taco seasoning and water; simmer until the liquid has completely evaporated, then take off the heat.
Place the seasoned beef, cubed Velveeta, and drained diced tomatoes with green chiles into the prepared slow cooker.
Stir everything together, then cook on low until the cheese has fully melted, approximately 1 to 1½ hours.
Switch the slow cooker to warm for serving; offer with tortilla chips.