In an Instagram story shared on the Albion defender's account, he shared images of two separate users sending vile abuse via direct messages.
The messages appear to have been sent following Albion's 2-1 defeat to Liverpool on Sunday, in which Ajayi started and played the full 90 minutes.
In the post, Ajayi called on Instagram to step up in the fight against online abuse. It comes just weeks after football clubs, players, national governing bodies, journalists and others took part in a social media boycott in a united stand against such abuse.
"Yet again, I come on Instagram to more racial abuse after a game. @Instagram sort it out." Ajayi said, in the post.
This makes Ajayi the latest player to be targeted online, after fellow Albion players Romaine Sawyers and Callum Robinson were both sent racist messages this season.
Other players, including but not limited to Tyrone Mings, Marcus Rashford, Wilfried Zaha, Willian, Anthony Martial, Reece James, Yan Dandha and Axel Tuanzebe have also been targeted with similar racist abuse.
Facebook, which own Instagram, has previously announced tougher measures to tackle the issue.
They include disabling accounts of those found to have repeatedly sent abusive messages via the platform.
Kingswinford man Simon Silwood is due to stand trial in September accused of sending an offensive message to Sawyers via social media.