The "This Is Us" star shared a photo of himself and his actress girlfriend on the social media app in celebration of New Year's Eve on Thursday.
In the black-and-white photo, the couple, dressed to the nines, cuddles up with wide smiles on their faces.
"Last minutes of 2020 here in LA," wrote Heartley, 43, in the caption. "Bring on 2021! Happy New Year!"
Hartley's post actually came just a few hours after Pernas, 31, actually shared her own photo of the two happy lovers.
Her post was in color, and also featured herself getting close to her man while outdoors.
"Sayonara 2020, it’s been real," the caption said. "Happy New Year from our quarantine den to yours."
The two actors began dating in May, according to a source that spoke to People magazine.
Hartley appeared on Radio Andy on SiriusXM Radio back in October and talked about his life and admitted he's been "really happy."
"I'm happy with my career. I'm happy with my personal life," he said. "I'm healthy, I'm safe. ... I mean, all of those things. So I'm very thankful."
The Instagram debut comes just over a year after Hartley split from his wife Chrishell Stause.
Stause, 39, alleged during an episode of the reality show "Selling Sunset" that she learned that Hartley had filed for divorce over text.
"I found out because he text[ed] me that we were filed," Stause tells her co-star Mary Fitzgerald in a tearful clip from the third season of the Netflix series. "Forty-five minutes later, the world knew."
She continued: "Because of the crazy way in which this went down, people want answers, and I f—king want answers."
The real estate professional then opened up about the conversation she had with Hartley, 43, after he texted her about the divorce filing.
"I talked to him right after ‘cause I thought that must be a joke, but that was kind of the end of the communication. What am I supposed to say? What do you say after that?" Stause recalled.