Mr Bernstein was a well-known and loved e-sports player and had 960,000 followers on streaming site Twitch.
His brother Gary Bernstein confirmed that Reckful had taken his own life, aged 31.
Twitch said Reckful was a "streaming pioneer" and that it was "devastated" to hear of his death.
Mr Bernstein had built his following in part by playing World Of Warcraft.
When his death was reported on Thursday evening, fans held virtual memorials inside the game.