Sessegnon, who joined the Bundesliga club on loan from Spurs in October, said he was disgusted by the abuse.
"Everyone at the club is with you @RyanSessegnon. We are proud of the rich ethnic diversity that exists across our communities, fans, staff and players," Spurs tweeted.
Everyone at the Club is with you @RyanSessegnon.— Tottenham Hotspur (@SpursOfficial) November 3, 2020
We are proud of the rich ethnic diversity that exists across our communities, fans, staff and players.
We are driven by inclusion and equality for all and nobody should have to endure such repulsive abuse. pic.twitter.com/Tliv3rdRtI
"We are driven by inclusion and equality for all and nobody should have to endure such repulsive abuse."
Hoffenheim said on Twitter they stood for "tolerance, integration and respect" in all areas.
"We reject any form of racism, discrimination and exclusion and say no to racism," they added.
Today, our player @RyanSessegnon was the target of horrific online racist abuse.#TSG stands for tolerance, integration and respect. We reject all forms of racism, discrimination and exclusion and say #NoToRacism! pic.twitter.com/mb6yvSk4Yg— TSG Hoffenheim EN (@tsghoffenheimEN) November 2, 2020
The 20-year-old posted a screenshot of direct messages sent to him with the abuse on his Instagram story.
"Honestly unbelievable. The craziest thing is I'm not even surprised anymore. Disgusting," he captioned the picture.
Crystal Palace defender Patrick van Aanholt and winger Wilfried Zaha are among players to have called on social media platforms to take stricter action against racism after they were targeted.