"I lost you to the summer wind," the "Problem" singer wrote late at night Tuesday announcing his departure.
Grande thanked her friends for all of their support via Twitter.
thank you for your continuous love & light over the past few weeks... we did lose my favorite person to ever exist yesterday, my grandpa :'(— Ariana Grande (@ArianaGrande) July 23, 2014
"If only y'all knew how amazing he was.. my [heart] hurts so much. It's beyond broken :'( but I got to hold his hand and watch him find his peace," she continued.
The former Nickelodeon star said that losing her grandfather "is the hardest thing imaginable" adding that she's still grateful that she got to spend time with him and her family.
Grande, 21, has continued to mourn online by sharing photos throughout the day.
In one of her last posts, the singer said she asked her grandfather last week if he wanted the family to pull her brother Frankie from Big Brother.
"He said 'no way!,'" she tweeted. "He's gotta play the game even tho i don't understand it."