Bellingham shared a screenshot of the racist emojis and derogatory comments about his mother sent to him, with the caption "Just another day on social media..."
Dortmund, Cologne, Bellingham's former club Birmingham City and the England national team all showed support for the 17-year-old.
"We continue to be disgusted by the discriminatory abuse our players -- and others across the game -- are being subjected to online," England tweeted. "Something needs to change."
Several players in the English Premier League, including Manchester United's Marcus Rashford, Chelsea's Reece James and Crystal Palace's Wilfried Zaha, have been racially abused online in recent months.
The increase in online abuse of players has prompted English soccer bodies to put pressure on social media companies to tackle the problem.
Instagram last month announced measures to deal with online abuse, including removing accounts of people who send abusive messages, and developing new controls to help reduce the abuse people see.