The actress, 39, is engaged to the Tony Award-winning actor, 44.
Dewan and Kazee both shared the happy news on Instagram Tuesday with a photo of the couple sharing a kiss.
“A lifetime to love and grow with you…you have my heart ❤️” Dewan wrote in her caption.
“When you wake in the morning I will kiss your face with a smile no one has ever seen,” Kazee wrote in a caption of his own, quoting the song “Let It Breathe” by Water Liars. “When you wake in the morning I will kiss your eyes and say it’s you I have loved all these years.”
In the photo, Dewan also gave fans a look at her impressive and unusual engagement ring. The star said “yes” to a gold-banded ring that Bayou with Love founder Nikki Reed helped Kazee create.
Dewan and Kazee’s engagement comes as they are already expanding their family. The happy couple revealed they were expecting their first child together in an interview with PEOPLE, which they announced in September.
The former Step Up actress already has a 6-year-old daughter, Everly, with ex-husband Channing Tatum, 39.
“We are beyond overjoyed and couldn’t be happier to be expanding our family!” Dewan and Kazee told PEOPLE exclusively about their pregnancy.
The couple began dating in October 2018, a few months after Dewan and Tatum announced their separation in April.
Dewan then made their relationship Instagram official in June of last year, posting a sweet photo of the pair sharing a hug.
“Speaking of peace….❤️” she captioned the affectionate snapshot.
A source told PEOPLE at the time the actress’ relationship to Kazee was “very serious.”
“So many things had to work for her to even consider dating again. And everything has clicked with Steve,” the source said.
“[Steve] is very supportive of her as a mom,” continued the insider. “He is amazing with Everly. Jenna loves having Steve around. She feels very lucky to be dating him.”
While Kazee and Dewan have largely kept their romance out of the spotlight, they haven’t shied away from expressing their love for one another on social media.
RELATED VIDEO: Inside Jenna Dewan and Steve Kazee’s Sweet Love Story — ‘It Was an Immediate Connection’
Last week, Kazee shared a tribute to Dewan on Valentine’s Day with a photo of the pair about to kiss.
“My whole 🖤 ” he wrote in the caption. “I love you. Thank you for being in my life. Thank you for letting me be in your daughters life. Thank you for bringing this new little life into the world. Thank you for loving me like you have. You have healed me with your heart. Happy Valentines Day.”
Dewan also expressed her affection for her new fiancé on the holiday of love.
“You flew into my life like a rocket, lit it up beyond what i could’ve expected or imagined, and every day i am in awe over the love, care and nurture you show me, Evie and everyone around you,” she wrote on Instagram alongside a black-and-white photo of the couple.
“I’ve told you a thousand times and I’ll tell you again..Thank you for finding me i am the luckiest girl alive❤️” she added.
The duo moved in together on December 3 — Dewan’s 39th birthday.
“The day of her birth has been a full one for us so far…dropping off the kiddo at school, baby doc appointment, nursery planning, moving into our new home, picking the kiddo up from school and so many other little life moments,” Kazee wrote on Instagram, hinting at his future proposal by adding, “Through it all I love catching eyes with her and knowing that she is the person I will be spending the rest of my life with.”