Justin Bieber and Hailey Bieber are now four years married.

The 28-year-old artist and the 25-year-old model marked the relationship milestone with sweet greetings on social media. On their respective official Instagram accounts, they paid tribute to each other and accompanied their posts with photos.

The “Sorry” singer uploaded a black-and-white selfie of him and his wife lying next to each other. Included in the photo is a puppy, which lies between them, with People describing it as "adorable."

In the caption, Justin Bieber called the Rhode founder his “best friend” and “wifey.” He also thanked her for “making [him] better in every way.”

The “Stuck With U” singer’s post, which surfaced on Tuesday, has since amassed more than 2.1 million likes. It has also obtained over 22,000 comments, with fans and followers making their support toward the couple known.

Hailey Bieber, for her part, shared a series of snaps featuring her and her husband to mark the anniversary.

One of the pictures is from the two celebrities’ second wedding, which occurred a year after they first tied the knot. It shows the model and the artist sharing a kiss, with her veil that read “Till Death Do Us Part.”

The Rhode founder captioned the post with a short yet touching message for the “Yummy” singer. She wrote, “4 years married to you,” and referred to him as “the most beautiful human [she has] ever known.”

In the same post, Bieber, formerly Baldwin, also called Justin Bieber the “love of [her] life.” She ended the piece by thanking God for him.

The model’s anniversary post has received over 4.3 million likes. It has also obtained more than 23,000 comments, and most of the commenters appeared to have congratulated and greeted the couple.

In August, Hailey Bieber spoke to Harper’s Bazaar and opened up about her marriage. The publication noted that the interview occurred four years since she and Justin Bieber got engaged.

The model told the magazine that her husband is “still the person that [she wants to] be rushing back to,” adding that she could not “wait to back and hang out,” especially when she had to fly somewhere else for a job.

Bieber also stated that her husband is her “best friend,” although she noted that “it still does take a lot of work to make it work.”

Justin and Hailey secretly tied the knot in September 2018, two months after announcing their engagement. They held a second wedding a year later, and had family and friends as guests.