Heigl left Grey's Anatomy earlier this year to spend more time with her family.
Chambers, who plays Alex on the show, has now explained that he enjoyed starring alongside the actress.
"I miss her all the time," he told E! Online. "She's such a great actor. She's so fun to work off of. I miss working with her."
However, Chambers suggested that Heigl's character Izzie will still be referred to in the show as Alex struggles to get over her.
"I think that's a couple on television that people will always remember," he said. "There's not much Alex without her. I think he'll be mourning Izzie for the next two seasons."
Chambers also praised Heigl and argued that the criticism she receives is "unfair".
"She admits that she has a mouth on her, but she's got a heart much bigger than her mouth," he said. "It's so unfair because I think people have taken her the wrong way. She's actually a good person. She's very funny and kind."
> Heigl: 'Grey's exit was hard choice'