Princess Beatrice and Eugenie have "cried together" over cruel taunts.
The two princesses - who are the daughters of Prince Andrew and his ex-wife Sarah Ferguson - admitted being in the public eye has meant they have "had to learn some lessons the hard way" but they have always been able to rely on one another for support.
Speaking at the WE Day UK event at the SSE Arena, Wembley, in London on Wednesday (07.03.18) morning, Eugenie said: "As young working women in the public eye we've had to learn some lessons the hard way. In many ways, we are grateful for that...in hindsight, naturally [laughs].
"It taught us to be strong, to value those around us, who love us and support us unconditionally."
Beatrice, 29, added: "I don't believe that there are many things in life that can make you feel more vulnerable, more helpless, more alone, than being bullied.
"It comes in many, many different forms, we've all suffered our fair share along the way. Growing up in the public eye means that every embarrassing, slightly awkward, growth spurt or hilarious fashion moment are published around the world.
"Together we have laughed, together we have cried. Ultimately though, together we fuelled each other's sense of humour when stones are being thrown. We reassure each other that people don't often understand how hurtful they can be in the world we live in today."
Eugenie - who recently got engaged to boyfriend Jack Brooksbank - went on to hail her older sister as an inspiration and spoke of how much she helped and supported her when she underwent surgery for scoliosis, a curvature of the spine, when she was just 12 years old.
The 27-year-old princess said: "As my big sister, you inspire me. I love that as a team we work hard to support each other, no matter what. When I was 12, I was diagnosed with, and treated for, scoliosis, and I have lived with two twelve inch metal rods in my back.
"It could have impacted my life and stopped me from doing the things I love. You encourage me not to get disheartened, not to give up, to live fearlessly. Today I am so lucky to get to work with, and support other young women who are going through the same thing. To encourage them, to not let their diagnosis win. To live fearlessly too.
"So WE day, the first lesson, is never give up!
"No matter what obstacles are put in your way, whether it's a life changing operation or a small bump in the road remember, you can all do it."
The pair went on to share the final message of encouragement which they live by, assuring the crowd that they aren't alone in the obstacles they might face.
Princess Eugenie said: "Our final lesson, is the one we have benefited from the most. You don't have to face anything alone".