In a large bowl, whisk together the instant vanilla pudding mix and milk until well combined and slightly thickened.
Gently fold in the thawed whipped topping until no streaks remain.
Add the drained crushed pineapple and chopped pecans (if using) to the mixture and stir to combine.
Carefully fold in the orange sections.
Cover the bowl and refrigerate for at least 30 minutes to allow the flavors to meld and the dessert to chill.
Serve cold. Enjoy your delicious Orange Fluff!
Notes
This dessert can be made ahead of time and stored in the refrigerator for up to 2 days. For a richer flavor, you can use full-fat milk and whipped cream.