The mother-daughter duo adorably revealed their joint magazine cover last week, with Heidi gushing over the celebratory moment via Instagram.
"I'm so proud of you. And not because you chose this path. I know that no matter which way you go, it will be your own," the supermodel wrote in German. "You always know exactly what you want and what you don't want. You are not a mini-me. And I'm happy for you that you can now show who YOU are."
"I know that being my daughter is not always easy. You never had the opportunity to grow up 'normally.' But what is normal?" Heidi, who shares Leni with ex Flavio Briatore, added. "But you have the talent to get the best out of everything. And I would say: none of it harmed you - on the contrary: you are a self-confident young woman who fights for her goals. And even more important: you are a really great person with your heart in the right place."
Heidi continued on, explaining to Leni in her post that "an exciting time is waiting for you."
"Vogue is the best way to start the career you dream of," she raved. "And even if it is a little difficult for me to let go of you into this world, I will always do everything so that you are happy and that your dreams come true. I am proud to be your mom!"