Mwepu fell ill on a flight to Zambia to join up with his teammates during the most recent international break and spent time in hospital before returning to the Seagulls to undergo further testing.
The tests revealed a hereditary heart condition which had not been picked up on in previous checks, with Brighton outlining the midfielder would be at an "extremely high risk of suffering a potentially fatal cardiac event" if he were to continue his playing career.
In a statement announcing his retirement, Mwepu explained it is his intention to remain in football in some capacity after being forced to hang up his boots.
"A small boy from a Zambian township called Chambishi has some news to share," he wrote. "He stood strong to follow his dream of playing football at the highest level and by the grace of God he lived his dream by reaching the Premier League.
"Some dreams however come to an end, so it is with sadness that I announce the need to hang up by boots because of the medical advice I have received. This is not the end of my involvement in football, I plan to stay involved in some capacity."
Brighton also released a statement, with club chairmain Tony Bloom saying: "We are all absolutely devastated for Enock. He and his family have had a traumatic few weeks and while we are just thankful he has come through that period, he has seen such a promising career cut short at such a young age.
"As a club we will give him all the love, help and support we possibly can to make a full recovery, and then as he decides on the next steps in his life."
"I am so sorry for Enock," manager Roberto De Zerbi added. "Before I arrived I looked at all the squad, and he was a player I was so excited and looking forward to working with. We will do everything we can to help him."
Mwepu joined Brighton from Red Bull Salzburg on a four-year deal in July 2021.
He made 27 appearances for the club and featured in six of their Premier League games this season.
