The club announced Thursday that the Ivorian international is set to undergo surgery after suffering an Achilles tendon injury in training. The rehabilitation period will be "extensive," Everton said in a statement.
The 24-year-old could miss at least six months, according to BBC Sport's Phil McNulty, marking a third significant blow for the Toffees' ball-stopper since joining the club last summer.
A £25-million signing from Mainz, Gbamin began his tenure with Everton in August, making two appearances before picking up a quadriceps injury. He then aggravated the ailment in October and required surgery, ending his first season in the Premier League.
"The injury, sustained in a non-contact situation at USM Finch Farm, is unrelated to the quadriceps problem Gbamin had been working his way back from since August last year," Everton's statement adds.
Gbamin was lured to Goodison Park amid lofty expectations to provide cover for Paris Saint-Germain bound Idrissa Gueye.