The 38-year-old reportedly died in a paragliding accident in Utah. Authorities said Thompson went for an adventure in Sand Hollow State Park Monday but failed to return home. His family then filed a missing persons report and his body was discovered Tuesday.
Thompson was wearing a GPS tracker, which officials were able to use in order to find his remains in a remote area of the park.
His video gear was taken by authorities at the scene, who said they will attempt to piece together how he passed.
On Tuesday, the King of Random Instagram account posted a photo of Thompson, writing, "It is with great sadness to inform everyone that Grant Thompson passed away last night."
The post urged people to "do a random act of love or kindness today" in honor of Thompson.
YouTube itself also paid tribute to him on its Twitter account, writing that it was "deeply saddened" by the loss of Thompson and calling him "a gifted, passionate and endlessly curious creator."
The King of Random channel has more than 11 million subscribers on YouTube.
Thompson is survived by his wife and four children.