The 31-year-old beauty - who has 11-month-old daughter Luna with her husband - recently penned an essay about her painful battle with the condition and John is ''glad'' she was so candid about the issue.
He explained: ''I'm glad she wrote about it. I think it was powerful for her to let a lot of women know they're not alone, and no matter how much money you have or fame, anybody can feel that.
''And it's hard for anybody no matter how successful you are and how many resources you have.''
John, 38, did his best to support Chrissy and to understand her postpartum depression battle.
He told People: ''For me as a husband, it was my job to do the best I could to support her and understand what she was going through and do whatever I could do to help her. I feel like that's the least I could do.''
And the Grammy Award-winning star has encouraged partners and other family members to read about postpartum depression in order to provide the best support possible.
The 'All of Me' hitmaker said: ''[As a man] you don't know internally what it feels like. You should read about it and understand what it is and really just be there to help.
''You need to be present and you need to be compassionate. And we're all learning and trying to figure it out as we go. At least do that and try to figure it out together.''
In her revealing essay for Glamour magazine, Chrissy recalled the moment she was diagnosed with postpartum depression.
She shared: ''I looked at my doctor, and my eyes welled up because I was so tired of being in pain ... My doctor pulled out a book and started listing symptoms. And I was like, 'Yep, yep, yep.' I got my diagnosis: postpartum depression and anxiety ...
''I remember being so exhausted but happy to know that we could finally get on the path of getting better. John had that same excitement. I started taking an antidepressant, which helped. And I started sharing the news with friends and family - I felt like everyone deserved an explanation, and I didn't know how else to say it other than the only way I know: just saying it. It got easier and easier to say it aloud every time.''