The actress – who plays Alex Dunphy in the sitcom – chose to have her 32F size reduced to a 34D after suffering from pack and neck pain over the years.
She revealed her new figure over the weekend at D23 Expo, the ultimate Disney fan event, where all things Disney are brought together under one roof. Modern Family airs on ABC in the US, which is owned by Disney.
Ariel, 17, looked lovely in a fitted green playsuit, with perfectly glossy, wavy locks and flawless make-up. Proving what a down-to-earth star she is, she spent time reading stories to a group of young children before posing with a Disney princess.
She told the new issue of Glamour magazine that she had the surgery in June: "It's amazing to finally feel right. My neck was hurting so bad and I actually had some problems with my spine. I had been discussing my chest with doctors for many years, but when I finally said, 'I'm thinking of doing this', he said, 'Your back is going to thank you so much'."
Ariel later thanked Glamour for allowing her to tell her story, adding: "To my fans, you guys have all been so supportive and I couldn't thank y'all more. You are all amazing human beings and I'm honoured to have you. HUGE thanks go to the people who support me, love me, and take care of me in every way possible.
"Lastly, never be afraid to speak your mind. Always make decisions because YOU want to, and always do what makes YOU happy."
Thank you so much @glamourmag and @JRadloff. I feel so blessed that you gave me a chance to share my story. I am extremely humbled. Jessica you are amazing!!!! To my fans, you guys have all been so supportive and I couldn't thank y'all more. You are all amazing human beings and I'm honoured to have you. HUGE thanks go to the people who support me, love me, and take care of me in every way possible. To my incredible sister @shanelle_gray, her husband @davidbarrygray, my beautiful baby nieces, the love of my life @laurent_claude_gaudette and our furry babies Casper and Rocco, my father Glenn Workman, and my best friends @jessiebergg, @huntershocket, @ohmyskyy, and @music4joejoe who have been by my side through everything, THANK YOU GUYS SO MUCH! I love you all more than anything. I don't know what I'd do without you guys❤️ Thanks is also in order to my awesome team who works so hard for me all the time. I wouldn't be where I am without them!!! Thank you!!! Lastly, never be afraid to speak your mind. Always make decisions because YOU want to, and always do what makes YOU happy. Xx Hair by @bobbyeliot/Makeup by @kristeeliu/Styling by @Anita Patrickson & Jordan Wright/Photos by @collinstark and @jessicastark_ http://www.glamour.com/inspired/blogs/the-conversation/2015/08/ariel-winter-breast-reduction?mbid=social_fb_fanpage