The 36-year-old French designer posted a photograph on Instagram showing his entire upper body, arms and head wrapped in bandages, with just his face exposed.
Rousteing said he “did everything to hide this story from as many people as possible” because he felt “so ashamed” of his scars from the injury.
Writing on Saturday, he said: “I finally feel ready to share this. I’ve been hiding this for too long and it’s time for you to know.
“Exactly a year ago, the fireplace inside my house exploded. I woke up the next morning in Paris’ Hospital Saint Louis.
“The talented staff at that famous hospital, which was dealing with an incredible number of Covid cases at that same time, took amazing care of me. I cannot thank them enough,” he added.
Rousteing said he hid his injuries from his “teams and friends”, adding: “To be honest, I am not really sure why I was so ashamed, maybe this obsessions with perfection that fashion is known for and my own insecurities.
“As I recovered, I just worked day and night to forget and creating all my collections, trying to keep the world dreaming with my collections and at the same time, hiding the scars with face masks, turtlenecks, long sleeves and even multiple rings on all my fingers through many interviews of photoshoots.”
He said the experience made him realise that social media gave him the power to “reveal only what you want to show”.
“Kind of allowing us to create our own special narrative that avoids what we do not wish to see or show: This is our new world,” he continued, adding that he is now “healed, happy and healthy”.
Rousteing, who became Balmain’s creative director in 2011 at the age of 25, said his recent Spring/Summer fashion show on 29 September was about “celebration of healing over pain”.
He thanked the production team and models and his “Balmain family” for “not only my 10 years of Balmain but my rebirth”.
“Today, I feel free, so good and so lucky,” he wrote. “I’m beginning a new chapter with a smile on my face and a heart full of gratitude.
“To the doctors and nurses at Saint Louis, and to all those who helped me during this long recovery and kept my secret: a profound thank you. I love you all.”
Friends and fans of Rousteing left messages of support on his post. Donatella Versace wrote that she was “so glad you’re safe”, while members of the Kardashian family including Kim and Kylie Jenner sent the luxury designer love.
Kris Jenner wrote: “You have been so strong and so positive through it all and I am beyond proud of you!
“I know how hard this is to share, but just know it will help so may people in different ways… Your message of hope and strength and focus and love will always inspire everyone who you come in contact with.. you are such a ROCKSTAR and I love you! God is so good.”