Appropriate birthday wishes for a niece include "Good thing I'm not your mom/dad because I like playing the cool aunt/uncle. Happy birthday!" and "Happy birthday to my dear niece. We make an awesome twosome!" Another good birthday wish for a niece is "Generation gap? Not with you around! Happy birthday!"
One good birthday wish for a niece is "You are my NIECE--Naughty, Impatient, Energetic, Cute and Expressive. I love you. Happy birthday." Another appropriate birthday message for a niece is "I am officially allowed to allow you to do the things your parents have not allowed you to do. Happy birthday."
Some birthday wishes for nieces focus on the special relationship between an aunt and her niece. One birthday wish that falls into this category is "May our aunt-niece relationship always make your mom jealous. Happy birthday." Another such birthday greeting is "An aunt-niece duo like us can give any mother-daughter pair a run for their money. Happy Birthday."
Some birthday wishes specifically for nieces from uncles include "I don't care about being the best uncle in the world. All I care about is making sure that my love for my niece is the best of the best. Happy birthday." Another good birthday wish from an uncle to a niece is "Pursue your dreams and give life your best shot. Never be afraid to fail, because your uncle's always got your back. Happy birthday."