Yes, walking can help slim your thighs by burning calories and reducing overall body fat. Consistent brisk walking, ideally for 30-60 minutes most days of the week, can contribute to weight loss, which includes slimming your thighs.
Walking also helps tone your thigh muscles, which can make your legs look more defined and sculpted. However, it's important to remember that spot reduction (losing fat in a specific area) is not possible. You can't target fat loss in your thighs alone. To slim your thighs, you need to reduce your overall body fat percentage through a combination of exercise and a healthy diet.
Walking is a great way to burn calories and improve your overall fitness, which can help you reach your weight loss goals and slim your thighs.