Prince Harry and Meghan Markle have been "shocked to their core" by stories they have heard from armed forces veterans struggling with mental health.
The prince was speaking at a conference about veterans' mental health at King's College in London.
He said many ex-forces personnel "continue to suffer in silence" and "their families also suffer".
But he added he was also "continually inspired by amazingly positive outcomes".
Prince Harry, who was an army officer for 10 years and served in Afghanistan, was giving the keynote speech at the conference.
He and his fiancee Ms Markle recently visited Colchester Garrison to learn about the work of the North Essex Veterans Mental Health Network, a collaboration between the NHS, charities and the MOD.
It was one of a number of private visits Ms Markle is making to charities in the run up to the couple's wedding on 19 May.
The prince said: "Some of the stories Meghan and I heard when we visited Colchester Garrison a few weeks ago shocked us to our core."
He said medical professionals and charities need to help veterans by sharing best practice and resources.
But Prince Harry, who set up the Invictus Games for veterans with disabilities, added he had been "privileged to witness the journey that many men and women have taken from desperation and isolation to amazing achievements, regaining self worth".
The prince wanted to dispel the "misconception" that mental health is the main issue veterans face.
He said: "A recent King's study shows us the proportion of veterans diagnosed with post-traumatic stress is very similar to the general population - with just 1.6% separating them."
He told the conference "employers value veterans and we want to push the message they are incredible assets to any business".