In a large mixing bowl, combine the halved grapes, diced apples, mini marshmallows, and chopped nuts.
In a separate bowl, mix together the Greek yogurt, whipped topping, honey, vanilla extract, and cinnamon until smooth and well combined.
Pour the yogurt mixture over the fruit and nut mixture, gently folding everything together until evenly coated.
Cover the bowl with plastic wrap and refrigerate for at least 1 hour to allow the flavors to meld and the salad to chill.
Serve chilled as a refreshing side dish or dessert.