Add cajun seasoning to a shallow bowl. Add steak and toss to coat with seasoning.
Heat olive oil in a large skillet over medium-high heat. Once hot, sear steak until edges are crispy and browned, 2-3 minutes per side. Take care not to crowd pan; work in batches if necessary and add more oil as needed between batches.
Remove steak from pan and set aside. Reduce heat to medium and add butter to skillet. Once melted, add garlic and cook until fragrant, just 1 minute, scraping up any bits from bottom of pan.
Remove from heat, return steak to pan, and toss with butter to thoroughly coat. Enjoy!