The 50 Shades Freed star and the Coldplay frontman skipped the red carpet but were spotted showing plenty of PDA inside the event. Paul McCartney, Katy Perry and Paris Jackson were among the other stars in attendance.
"They walked in holding hands and Dakota was not letting go -- she was super into the PDA," a source said. "When Chris let go of her hand, she slipped her arm through his."
Us Weekly reported Johnson and Martin remained "nearly inseparable" throughout the night.
"Dakota and Chris were super affectionate with each other," an insider said. "She was whispering in his ear, rubbing his back and was super smiley. She seemed happy to be there with him."
"[They] never really left each other's side or stopped holding hands," the source added. "There was one moment when Dakota motioned for two friends to come near them and that was the only time they really separated."
Johnson and Martin were first linked in October, and appeared to confirm their romance Sunday with an affectionate outing in Malibu, according to TMZ. The singer's ex-wife, actress Gwyneth Paltrow, confirmed her engagement to Brad Falchuk this month.