Matthew shared a post to Instagram in which he wrote a passionate statement on the subject.
In the picture Matthew wrote: "As someone who has openly talked about my battles over the years with depression, I thought it only proper to put a little post out there on such an important day #worldmentalhealthday2019."
He continued: "Only three weeks ago I lost a friend to suicide, he was 52 and outwardly the happiest, funniest, friendliest man you could meet. You never know what someone is going through on the inside.
"I'm no expert, but if I can offer up a tiny bit of help, here's my suggestion... Don't suffer in silence; talk... to anyone. If you don't feel you want to talk to a friend, family member or doctor, there are some incredible organisations and people out there who will listen.
"Don't be embarrassed about talking about mental health. Be open, talk, it WILL help."
Don't be embarrassed about talking about mental health. Be open, talk, it WILL help.
He then added links to the Samaritans and Barnado's websites before signing the note.
Fans quickly commented on the post. One wrote: "Sending love."
A second commented: "This is so important."
Matthew joined Emmerdale in 2006 as David.
In real life, Matthew is married to his co-star Charley Webb, who plays Debbie Dingle in the ITV soap.
They are also parents to Buster, nine and Bowie, three.
Charley is currently on maternity leave and her character Debbie moved to Scotland to run a garage left to her by Lisa Dingle.
If you are struggling or are concerned about someone who might be, contact Samaritans FREE any time from any phone on 116 123, even a mobile without credit.
This number won't show up on your phone bill. Or you can email email@example.com or visit samaritans.org to find details of your nearest branch, where you can talk to one of their trained volunteers face to face.
Leave us a comment on our Facebook page @EntertainmentDailyFix and let us know what you think!