Gigi Hadid made an appearance on Tuesday night's episode of Bravo's hit reality TV series "The Real Housewives of Beverly Hills." The model attended the Global Lyme Alliance gala with her mother Yolanda Foster and her younger siblings, sister and Bella Hadid and brother Anwar Hadid, who are both models, and she gave a speech in honor of her mom and her battle with Lyme Disease.

Foster has been open about her health struggle throughout the entire season, which has been a cause of tension between her and her cast mates because they think that Foster is over-exaggerating her illness. However, Foster's symptoms are real, and her use of her platform as a reality TV star to spread Lyme Disease awareness earned her an award at the gala, which was presented to her by her oldest daughter Gigi.

"The Global Alliance is hope, and tonight, we're honoring the person that, more than anyone I know, is hope for Lyme Disease Awareness, my mom," the 20-year-old Victoria's Secret model said, choking up. "For your fight, for your passion, and for making your journey one that will help so many, I am so honored to honor you with this award. I love you."

Foster and 19-year-old Bella sat at their table in the audience, listening to Gigi's speech with tears in their eyes. When Foster took the stage, she embraced Gigi before taking her place behind the podium.

"Thank you Gigi, thank you for exceeding everything I hope, everything I dream and every expectation I ever had for you," the proud mom tells her daughter in front of the entire room.

Foster thanked her then-husband David Foster and revealed that her two youngest children, Bella and her 16-year-old son Anwar were also diagnosed in 2012 with chronic Lyme Disease. Her cast mate Kyle Richards- who was sitting at the same table with Foster and her children- held a napkin to her face and wiped tears from her eyes.

"It's really hard because a part of me feels guilty for talking about her children," Richards says, mentioned various instances throughout the season where the cast members doubted their Lyme Disease diagnosis, too. "It was really upsetting and I just want her to know that I felt bad."

"This is my promise to you," Foster told her children during her speech. "I will continue to search the globe until we find a cure affordable for all."

Watch the clip from last night's episode of "The Real Housewives of Beverly Hills" below.