The film explores the various roles Williams made famous over the years, as well as a look at the actor's struggle with substance abuse.
'The genius of Robin Williams lay in his ability to make a room, a comedy club, a concert hall or the whole world laugh,' said a statement by HBO.
'Family, friends and film crews often saw a man who wasn’t happy unless everyone else was having a good time — but the dualities Williams embodied were present inside him at all times.'
The documentary also features in-depth interviews with a range of Williams' famous friends, including Billy Crystal, Eric Idle, Whoopi Goldberg, David Letterman, Steve Martin, Pam Dawber and his son, Zak Williams.
"The world is a darker and lonelier place for a lot of us, for a lot of reasons,' said Crystal.
Adding: 'Rejoice in the fact that you had [Williams] for as long as you did. Rejoice in the fact that you witnessed some really amazing comedy, some brilliant receptions, and he broke your heart in the same way as an actor.'
Williams passed away in 2014 after it was revealed he'd been suffering Lewy Body Dementia.
Robin Williams: Come Inside My Mind debuts July 16 on HBO.