The 22-year-old was left out of the England squad this week, leading to the inevitable avalanche of opinions about him on traditional and social media platforms.
Bellingham, speaking as a Laureus Ambassador on World Mental Health Day, said he once would be checking his phone to read what people were saying about him on social media, but now largely ignores it.
"As a young player at Birmingham (City), I used to put my name into Twitter and read everything.
"But even if the comments were positive, I quickly decided: Why should I let the opinion of people who don't know me validate how I think about myself?" he said.
"I believed I was a good player before reading it on Twitter - so what was the point in reading other people saying it?
"Of course, if I came across negative comments, it would have the opposite effect. So, again, I asked myself: Why am I putting that on my own mental health?
"There's enough negativity and pressure in professional sport that you don't need to seek it out. Now, when I do read negative comments, it doesn't affect me - but I'd still rather not see them."
Bellingham said social media is an important tool in becoming more relatable to the public, but also believes there is a 'shut up and take it' attitude when it comes to online hate.
"With the development of social media, there are more ways to attack someone, to make them feel down, and I think there's still a stigma around talking about mental health," he said.
"I know there've been times where I've felt vulnerable, doubted myself and needed someone to talk to - and, instead, I've tried to keep up this macho athlete image of 'I don't need anyone'.
"The truth is, I do - everyone does. And you'll feel a lot better from talking about your feelings and emotions.
"As athletes, it seems like we have the world at our feet - we can do whatever we want, earn so much money, and never be affected by it.
"But the reality is if we can show vulnerability, then it opens up a bigger conversation for people who are struggling in the darkness."