Preheat your grill to medium-high heat. If using a grill pan, heat it over medium-high heat on the stovetop.
In a small bowl, mix together the Cajun seasoning, garlic powder, onion powder, smoked paprika, salt, and black pepper.
Pat the salmon fillets dry with paper towels. Drizzle olive oil over the fillets, then sprinkle the seasoning mixture evenly on both sides of the salmon.
Place the salmon fillets skin-side down on the grill. Cook for about 4-5 minutes, then carefully flip and grill for an additional 3-4 minutes, or until the salmon flakes easily with a fork and reaches an internal temperature of 145°F.
Remove the salmon from the grill and drizzle with fresh lemon juice. Serve immediately with lemon wedges on the side.