Malone made the big announcement with a sweet photo of her hand cradling her son, Ode Mountain.
"One day, after all the youthful rushing quiets in your heart, you realize there’s nothing more you need," she captioned the cute pic, which included a ring on her right hand. "Nothing more you want to achieve than to build your life around love."
"And oh the things we will get to build together. I couldn’t be happier. I love you Ethan," she wrote, alongside the telling hashtag "#isaidyes?."
Malone and DeLorenzo announced the birth of their son in May with an adorable family photo on Instagram.
"The best weekend of our lives!!!" she captioned the photo of the couple gazing lovingly at their baby boy. "What an incredible blessing to be chosen by this amazing, kind, gentle and beautiful soul to be his parents. Humbled an in complete awe that we get to experience the most ancient and transcendent love that exists."
Malone isn't the only one gushing about an engagement.
ET recently spoke toSuits star Patrick J. Adams, who said that despite keeping details of his upcoming wedding to Pretty Little Liars star Troian Belissario super-secret, they're both "incredibly excited."
"We're going to make sure that everyone finds out about that long after it happens," he shared. "That's kind of our game plan… but obviously we're both incredibly excited. Once it does, we'll make sure that the world knows."
See what Bellisario had to say on their upcoming nuptials in the video below.