The 41-year-old singer and Elle, 30 - who tied the knot in 2019 - have revealed via an Instagram post that they're preparing to become parents later this year.
Alongside an image of her growing baby bump, the model wrote on the photo-sharing platform: "Our little family is growing...... and so is my belly. (sic)"
Elle also shared a photo of the pair kissing on her Instagram Stories.
She captioned the snap: "Our best kept secret since September."
Earlier this year, Matt announced he was taking a year off from touring to focus on his family.
Speaking about his future plans, the music star said: "I'm going to chill out, have some family time and maybe towards the end of the year write some songs and start the new album."
Elle and Matt first began dating in 2015 and the loved-up couple announced their engagement in December 2018.
The model - who previously starred in Robin Thicke's 'Blurred Lines' video - also revealed details of their engagement via social media.
Elle wrote on Instagram at the time: "Just a few days after my birthday, on the most romantic holiday of our lives, the man of my dreams asked me to marry him!
"After tears of joy, gasps of shock, and a split second of disbelief, of course- I said YES! I can't imagine our lives apart. What I can imagine is a bright future full of love & light, family & friends, moments that turn into cherished memories, and a lifetime of pure bliss. (sic)"
The celebrity duo subsequently tied the knot in a romantic ceremony in August 2019.