The 26-year-old had been absent from social media for the past weeks until he returned to Instagram on Sunday to post a video update.
Holland told his 67.7 million followers how the social media apps had become “detrimental” to him as he would continue to read things about himself online and “spiral”.
Watch: Spiderman star Tom Holland announces break from social media for mental health
The BRIT school graduate wrote: “Hello and goodbye... I have been taking a break from social media for my mental health, but felt compelled to come on here to talk about @stem4org .
“Stem4 is one of the many charities @thebrotherstrust is extremely proud to support - and I’d like to take a moment to shine a light on their fantastic work ... Love to you all, and let’s get talking about mental health.”
The post was met by many notes of well wishes and love, including from the musician Justin Bieber, writing: “Love you man”.
The actor, who is dating co-star and Euphoria actress Zendaya, shares his charity organisation, The Brothers Trust, with his siblings, Harry, 23, Sam, 23, and Paddy, 17.
The organisation are selling t-shirts that are fundraising to support charities such as Stem4.