Leni shared the exciting news on her Instagram, captioning it, "MEIN ERSTES COVER," which translates to "my first cover."
"Couldn't wait to buy one, or ten," she added.
Leni's mom also shared the love on Instagram. The 47-year-old wrote a lengthy caption in German, congratulating her daughter for this huge achievement.
Heidi also made a point of saying that Leni is not simply her "mini-me."
"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," she wrote. "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."
The Project Runway alum continued, "I know that being my daughter is not always easy. You never had the opportunity to grow up 'normally.' But what is normal?"
"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 did not shy away from boasting about this huge achievement either.
"Vogue is the best way to start the career you dream of," she wrote. "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!"